Someone recently asked if there was a neat way to see where all of the now broken down subreddits moved.
Some moved to Discord, some to Lemmy, and some are somewhere else.
This seems to be a good place to find your communities again: https://sub.rehab/
Response from the dev here. It sounds like they would rather not take a stance on the practicality of one service over another.
Oh, of course, you gotta tell people where communities went. I just find Discord a questionable alternative to Reddit.