No! You can self-host your own instance. I've tried to make it easy to setup. All you need is:
- PHP 7.3 or newer, with ext/sodium
- PostgreSQL 9.6 or newer
- Apache or nginx with LetsEncrypt (for HTTPS)
You can get the source code for free on Github.
If you want access to the instance I'm running at https://faq.dhol.es, I'm only giving invite codes out to close friends and Patreon supporters. Invited users are free to invite any of their friends.