The popularity of an Instagram video can affect its actual video quality: According to Adam Mosseri (the Meta executive who leads Instagram and Threads), videos that are more popular get shown in higher quality, while less popular videos get shown in lower quality. In a video (via The Verge), Mosseri said Instagram tries to show “the highest-quality video that we can,” but he said, “if something isn’t watched for a long time — because the vast majority of views are in the beginning — we will move to a lower quality video.”
https://techcrunch.com/2024/10/27/instagram-is-lowering-video-quality-for-unpopular-videos/