~~I'd assume it's a running joke~~

SyncForLemmy --> Sink for Lemmy

Ah just checked, maybe it's because the mods haven't checked in with the community in a while and it's a joke about being abandoned. From what I remember, even on Reddit the dev would disappear for some time and then come back with a big update?

If they ARE gone, there are a lot of Lemmy apps available that are receiving regular updates. Boost, Connect, and Eternity might be a similar feeling to Sync