Although one user there also makes the comment that it isn't:

GitHub

anytype-ts/LICENSE.md at main · anyproto/anytype-ts

Official Anytype client for MacOS, Linux, and Windows - anyproto/anytype-ts

Yes he's correct. Source available isn't a licence recognised either as free software by the FSF or as open source by the OSI. As its license currently reads, Anytype cannot even be legally used by everyone much less forked and distributed. Even Skiff's license was better in this regard...