A lot of privacy guides suggest avoiding Telegram. I understand that in its default mode there’s no E2EE (and no E2EE for groups at all). If people I know don’t wanttko use Signal, isn’t Telegram the lesser evil given it’s nicer privacy policy (than other popular ones)?
Say I use the FOSS version of it.
Despite you using the foss client of telegram there is no source for the server, signal has published it’s code.
Probably another point is that the encryption for Matrix/Element has undergone multiple audits, one in 2016 and another one of their newer rust library. Whereas telegram just has not. There was this also a not too long ago. MTProto is also used nowhere else, whereas a lot of encryption has been influenced by the Double Ratchet which is well understood.
The other thing worth noting is that Matrix is the foundation for other products which many governments use for secure communications.