My e-mail provider does this. I wanted to change my password to some 64 character long generated string. It accepted, but I could not log in after that. After a few tries, I found the reason and, after another few tries, also the limit at which it gets truncated: 16 characters! God, how I hate them for this…

Require traditional 1933 solutions!

A few years ago, I switched from WhatsApp to Signal. I told all my important contacts and groups that I’d delete WhatsApp at the end of the month and that they can either reach me on signal or using SMS from there on. This was enough time to answer peoples questions and convince many people to install Signal too. My family now uses it, most of my friends do, and while all of them kept WhatsApp back then, they now use Signal to message each other. So it is possible to make the switch and take lots of people with you.