This - "Cumulative Layout Shift" - is part of Google's Core Web Vitals - https://support.google.com/webmasters/answer/9205520?hl=en - so if people are doing that, they're going to be penalised by Google. (Although probably only a bit, given the number of other factors that go into search rankings).
Meuh - google does this with youtube. Load video: video centered. Oh there's a side bar, let's shift the video. Oh the contents needs a smaller dimension, let's shift again. Rather annoying if you're used to watching videos at more than default speed - the control for that shifts 2-3 times.
Google is so huge that, as we say in the UK, it doesn't know its arse from its elbow - the teams are so disparate that it would be difficult to coordinate. Besides which, the "other factors" that I mention heavily favour a site like YouTube, such as the enormous number of inbound links, to a point where they can ignore the inconvenient bits of Core Web Vitals.
