Web client doesn't load comments / sends posts

This is easily observable with https://cactus.chat/demo/

As this also happens with https://hyteck.de/post/cactus-chat/

and s2.hyteck.de (selfhosted cactus.chat server/webclient)

I suspect a change in browsers.

Details of the request failing:

GET https://matrix.cactus.chat:8448/_matrix/client/r0/directory/room/%23comments_cactus.chat_demopage%3Acactus.chat

fails with NS_ERROR_DOM_BAD_URI

and the option

OPTION filename /_matrix/client/r0/directory/room/%23comments_cactus.chat_demopage%3Acactus.chat

fails with CORS failed

Happy to help debugging. Tested on Mozilla Firefox 109.0 and Chromium 109.0.5414.74 Arch Linux