This is a helpful website for finding out where your subreddit communities moved to.

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/

The developers behind Lemmy have spoken up about the current situation regarding migrating users and the effect on their development process.

Two most important points from this imo:

• don't hammer them with pull requests, duplicate Git issues or questions because they got enough of those
• if you want things to move faster, give them money! They are focusing on user feedback and therefore don't have enough time to make a lot of money.

Edit: Here's a Patreon link to the Devs: https://www.patreon.com/dessalines