"Shaunteh Kelly, chief of media relations for the U.S. Army Military District of Washington, explained to Reuters via email why the soldiers in Biden’s ceremony weren’t wearing decorated jackets. The Bush and Obama ceremonies shown took place during warmer weather, and per Army regulation AR 670-1, awards and accommodations are allowed on ceremonial blouses, but not on ceremonial overcoats or raincoats."
"Shaunteh Kelly, chief of media relations for the U.S. Army Military District of Washington, explained to Reuters via email why the soldiers in Biden’s ceremony weren’t wearing decorated jackets. The Bush and Obama ceremonies shown took place during warmer weather, and per Army regulation AR 670-1, awards and accommodations are allowed on ceremonial blouses, but not on ceremonial overcoats or raincoats."
Here is AR 670-1 https://armypubs.army.mil/epubs/DR_pubs/DR_a/ARN30302-AR_670-1-000-WEB-1.pdf
You can go ahead and search it for "blouse" and "overcoat" and see that it doesn't mention what Shaunteh Kelly is talking about.