continuwuity/changelog.d/2189.feature.md

Removed the ability to run a server with "challengeless registration" (i.e. the big scary long config option, with no captcha, email, or registration token requirements), without manually compiling the server with non-default arguments. Contributed by @nex.

(This is part of a wider effort to reduce abuse in the Matrix network, of which servers that are easily automated cause a disproportionate amount of)