Well, it wouldn’t be a Pixel launch without some kind of issue. Personally, I don’t see this being an issue for me as I don’t really do much video. But just throwing it out there. Also, it looks like this was already an issue on the 5 and 4a 5G. Not sure why it’s blowing up now.
https://www.cnet.com/tech/mobile/oh-no-google-pixel-5a-has-an-overheating-problem/
https://www.androidpolice.com/2021/08/19/looks-like-the-pixel-5a-gets-too-toasty-while-recording-video/