He lists quite a few options, personally never used telegram and always saw it with the stigma of being used mostly by creepos (as heard from youtube true crime podcasts and whatnot)
Out of the 8 alternatives he's listing, the picks i would personally vouch for from being used professionally and regular no creepo people:
- Matrix (through the client Element, there's different clients for it as well)
- Session
- SimpleX
Doesnt mean career criminals wouldnt use those, I mean, it's like cars, bank robbers do be using the car technology too lol, but from experience with people using those professionally to do some actual legit dev work and whatnot, those would be my go to