@MrFlamey Give it some time. If you follow a lemmy community, all posts of that community will _from now on_ reach your Mastodon instance and be displayed there. There is no retroactive synchronization.
(The exception to this is when someone from your Mastodon instance already followed that community in the past: Then somebody else already did make those posts available to your instance and you can immediately see some posting history of that community.)
@MrFlamey Using your Mastodon account, you could even follow a lemmy community; and fav, boost and comment on their posts (like I did just with your comment). Just copy the URL to anything on the fediverse, paste it into the search box of your Mastodon client: you're good to go!
Longer explanation: https://toot.kif.rocks/@anathem/110565430770229960
@sexy_peach @vaprz Malicious Compliance by answering a request to re-open a subreddit with the same business-y language, citing other empty phrases typically employed by corporate mods.
@Teritz @mogoh Hallo Bochum, ich wohn aber inzwischen in der Nachbarstadt.