I totally agree. It was expected to see him leaving after causing Red Bull to finish the season at even the 3rd position. It is like Perez has already finished Formula 1 in his head. There are even some rumours out such as he will join Ferrari and race in WEC next season. I wouldn't be surprised though for the reason I said.
Now I'm curious about who is taking the seat officially. Tsunoda or Lawson. These are my candidates. The rumours were pointing to Lawson but I believe Tsunoda deserves it more with his ambition. We haven't watched Lawson as much as him yet.
I do not know who they will give the seat to, it doesn't feel like it makes sense at the moment for either because I do not see either being a great improvement. I honestly would try to grab Sainz but they were too late for that, Sainz was known to leave Ferrari like since start of the season, they should have gotten him, that would have been an amazing improvement. You can't deny that the guy who won races even against Max, in a worse car, couldn't be awesome, that dude could have been the perfect support driver for Max, but they dropped the ball on that one for sure.