So we have at least "SI"/"SIS" or ?S?I?/?S?I?S where ? is some other chars.
full output of exiftool ,maybe you notice more unusual chars in output.
ExifTool Version Number : 11.16
File Name : 1.jpg
Directory : .
File Size : 3.7 MB
File Modification Date/Time : 2021:02:20 09:32:48+01:00
File Access Date/Time : 2021:02:20 19:16:18+01:00
File Inode Change Date/Time : 2021:02:20 19:03:50+01:00
File Permissions : rw-r--r--
File Type : JPEG
File Type Extension : jpg
MIME Type : image/jpeg
JFIF Version : 1.01
X Resolution : 300
Displayed Units X : inches
Y Resolution : 300
Displayed Units Y : inches
Current IPTC Digest : f7ca898706b35cd3ba75201107430eea
Coded Character Set : UTF8
Application Record Version : 4
Keywords : USSF COMMISIONING CEREMONY
Time Created : 19:26:54
Digital Creation Date : 2021:02:11
Digital Creation Time : 19:26:54
Caption-Abstract : US Airforce Photo By RIchard Gonzales
IPTC Digest : f7ca898706b35cd3ba75201107430eea
Exif Byte Order : Little-endian (Intel, II)
Image Description : US Airforce Photo By RIchard Gonzales
Make : Canon
Camera Model Name : Canon EOS-1D X Mark II
Resolution Unit : inches
Software : Adobe Photoshop Lightroom Classic 7.1 (Macintosh)
Modify Date : 2021:02:11 16:15:50
Exposure Time : 1/8000
F Number : 5.6
Exposure Program : Manual
ISO : 800
Sensitivity Type : Recommended Exposure Index
Recommended Exposure Index : 800
Exif Version : 0230
Date/Time Original : 2021:02:11 19:26:54
Create Date : 2021:02:11 19:26:54
Shutter Speed Value : 1/8000
Aperture Value : 5.6
Exposure Compensation : 0
Max Aperture Value : 4.0
Metering Mode : Multi-segment
Flash : Off, Did not fire
Focal Length : 50.0 mm
Sub Sec Time Original : 83
Sub Sec Time Digitized : 83
Color Space : sRGB
Focal Plane X Resolution : 1520
Focal Plane Y Resolution : 1520
Focal Plane Resolution Unit : cm
Custom Rendered : Normal
Exposure Mode : Manual
White Balance : Auto
Scene Capture Type : Standard
Serial Number : 072012000256
Lens Info : 24-105mm f/?
Lens Model : EF24-105mm f/4L IS USM
Lens Serial Number : 000053ca78
Profile CMM Type : Linotronic
Profile Version : 2.1.0
Profile Class : Display Device Profile
Color Space Data : RGB
Profile Connection Space : XYZ
Profile Date Time : 1998:02:09 06:49:00
Profile File Signature : acsp
Primary Platform : Microsoft Corporation
CMM Flags : Not Embedded, Independent
Device Manufacturer : Hewlett-Packard
Device Model : sRGB
Device Attributes : Reflective, Glossy, Positive, Color
Rendering Intent : Perceptual
Connection Space Illuminant : 0.9642 1 0.82491
Profile Creator : Hewlett-Packard
Profile ID : 0
Profile Copyright : Copyright (c) 1998 Hewlett-Packard Company
Profile Description : sRGB IEC61966-2.1
Media White Point : 0.95045 1 1.08905
Media Black Point : 0 0 0
Red Matrix Column : 0.43607 0.22249 0.01392
Green Matrix Column : 0.38515 0.71687 0.09708
Blue Matrix Column : 0.14307 0.06061 0.7141
Device Mfg Desc : IEC http://www.iec.ch
Device Model Desc : IEC 61966-2.1 Default RGB colour space - sRGB
Viewing Cond Desc : Reference Viewing Condition in IEC61966-2.1
Viewing Cond Illuminant : 19.6445 20.3718 16.8089
Viewing Cond Surround : 3.92889 4.07439 3.36179
Viewing Cond Illuminant Type : D50
Luminance : 76.03647 80 87.12462
Measurement Observer : CIE 1931
Measurement Backing : 0 0 0
Measurement Geometry : Unknown
Measurement Flare : 0.999%
Measurement Illuminant : D65
Technology : Cathode Ray Tube Display
Red Tone Reproduction Curve : (Binary data 2060 bytes, use -b option to extract)
Green Tone Reproduction Curve : (Binary data 2060 bytes, use -b option to extract)
Blue Tone Reproduction Curve : (Binary data 2060 bytes, use -b option to extract)
XMP Toolkit : Adobe XMP Core 5.6-c128 79.159124, 2016/03/18-14:01:55
Rating : 5
Creator Tool : Adobe Photoshop Lightroom Classic 7.1 (Macintosh)
Metadata Date : 2021:02:11 16:15:50-08:00
Lens : EF24-105mm f/4L IS USM
Image Number : 0
Approximate Focus Distance : 4294967295
Flash Compensation : 0
Firmware : 1.0.2
Date Created : 2021:02:11 19:26:54.83
Document ID : xmp.did:85a7a681-fb93-497d-b88d-b4063b84ef0c
Original Document ID : AF8233F0EAA9ACE0675B7171E6EFBC92
Instance ID : xmp.iid:85a7a681-fb93-497d-b88d-b4063b84ef0c
Format : image/jpeg
History Action : derived, saved, converted, derived, saved
History Parameters : converted from image/x-canon-cr2 to image/jpeg, saved to new location, from image/jpeg to image/x-canon-cr2, converted from image/x-canon-cr2 to image/jpeg, saved to new location
History Instance ID : xmp.iid:f8b9cb9b-3279-42f5-a71a-238749bd6522, xmp.iid:85a7a681-fb93-497d-b88d-b4063b84ef0c
History When : 2021:02:11 16:15:50-08:00, 2021:02:11 16:15:50-08:00
History Software Agent : Adobe Photoshop Lightroom Classic 7.1 (Macintosh), Adobe Photoshop Lightroom Classic 7.1 (Macintosh)
History Changed : /, /
Derived From Instance ID : xmp.iid:f8b9cb9b-3279-42f5-a71a-238749bd6522
Derived From Document ID : xmp.did:f8b9cb9b-3279-42f5-a71a-238749bd6522
Derived From Original Document ID: AF8233F0EAA9ACE0675B7171E6EFBC92
Description : US Airforce Photo By RIchard Gonzales
Subject : USSF COMMISIONING CEREMONY
Image Width : 5185
Image Height : 3457
Encoding Process : Baseline DCT, Huffman coding
Bits Per Sample : 8
Color Components : 3
Y Cb Cr Sub Sampling : YCbCr4:4:4 (1 1)
Aperture : 5.6
Date/Time Created : 2021:02:11 19:26:54
Digital Creation Date/Time : 2021:02:11 19:26:54
Image Size : 5185x3457
Megapixels : 17.9
Scale Factor To 35 mm Equivalent: 1.1
Shutter Speed : 1/8000
Create Date : 2021:02:11 19:26:54.83
Date/Time Original : 2021:02:11 19:26:54.83
Circle Of Confusion : 0.028 mm
Depth Of Field : inf (15.68 m - inf)
Field Of View : 37.7 deg
Focal Length : 50.0 mm (35 mm equivalent: 52.8 mm)
Hyperfocal Distance : 15.68 m
Lens ID : Canon EF 24-105mm f/4L IS USM
Light Value : 14.9
oh, and funny side-note about the Space Force image ... it's title in the metadata is misspelled as "COMMISIONING" --> missing an 'S'.
Since misspellings are purposeful, seems like this would be a hint to look at what's missing (but props to the Anon who figured the proof first: https://greatawakening.win/p/12hRZjLZAu/space-force-17--decoded--15-of-1/ )
Also misspelling: author of photos. https://greatawakening.win/p/12hRZjLZAu/space-force-17--decoded--15-of-1/ There is no: "Richard Gonzales", there is: "RIchard Gonzales". Big "i"...
So we have at least "SI"/"SIS" or ?S?I?/?S?I?S where ? is some other chars.
full output of exiftool ,maybe you notice more unusual chars in output.
Also - I have a question why we not follow the way mentioned earlier in: https://greatawakening.win/p/12hRZjLZAu/space-force-17--decoded--15-of-1/
Were my look and u/RageBringer look at that not useful at all ?
/https://greatawakening.win/p/12hRZjLZAu/space-force-17--decoded--15-of-1/