It certainly happened in my previous employer which I left two years ago, but the thing is that it was really the straw that broke the camels back. People who were already annoyed/thinking about leaving left. People who had other options left.

But then, two years on, there are not really that many remote working options in the UK now - I don't live in London and work remotely for a large international company with staff all over the world. I'm sort of debating moving on but what I see is that most tech-y companies are advertising for hybrid 2-3 days a week in London, Manchester, Oxford, Cambridge. Which gives a much more limited pool of jobs for those who want to move on now who don't live in those areas. With that though, if you get through to an interview stage, you find out that while it's advertised as that, most people are not in the offices that much at all. I visit an office near where I live just to get out of the house where staff are nominally in three days a week, and it's deserted apart from on Tuesdays.