There does seem to be a very small "thump" that aligns with the shot from the window in the video, but it's quiet. One possibility is that this is a suppressed weapon, although given the lack of a more obvious noise, it would almost have to be using subsonic ammo. Suppressors will remove a lot of the noise from a rifle shot, but the sonic boom is still very loud, too loud to not get picked up by the camera here.

But suppressed rifles with subsonic ammo are very, very quiet, especially over the noise of a crowd where a small number of people are panicking and are very loud.

However, effective range becomes a major consideration with subsonic ammo. As an example, the most common subsonic rifle cartridge is typically .300 BLK (Blackout) and there you're talking an effective range of 150 yards or less, though an extremely skilled shooter that's experienced with the platform could probably stretch that a bit.

If we're able to get more context on this video in terms of exactly where it was at on the grounds and the President's positioning at the exact time of the shot, that will give us a better sense of whether a suppressed, subsonic platform was being used here.