@leocg Nevermind, I found the problem! Basically, I have an extension which automatically selects the best quality (YouTube Auto HD +FPS). The problem was that recently, youtube implemented an increased bit rate on some videos as the best option if you have youtube premium so my extension basically selected that increased bitrate option and, since I don't have youtube premium, everytime I interacted with the video, it re-selected that increased bit rate and thus prompted that popup. Thanks for your help!
Here's the prompt I keep getting, it appeares in 1 out of 4 videos and when I, for example, go five secconds back using the direction keys, it gets prompted again. Any solutions/explinations?