Speaking of dubious "secure" messengers there's Keet, which is closed-source and built by Bitfinex and Tether, who certainly has a very sketchy past. For example, they claimed for very long time to have 1:1 backing by USD, but we all know that was a fat lie. 🫩

Oh, and then there was that time when Bitfinex lost more than 100k BTC. Good times!!

So yeah, probably don't use that one, either. Not implying that you would, but still.