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/
If you’re on mobile, Jerboa on Android allows you to save posts. I don’t remember what the iOS equivalent app is but I’ve heard it’s good.