Can't pass valid avatar URL

URL to user's avatar in my Nextcloud (30.0.4) looks like this:
https://mynextcloud.com/index.php/avatar/username/512

I can't (or maybe i just don't know how?) get link without '/512' (or some other numer) at the end.
So to pass whole URL - with username in proper place - to Discourse i have to fill config form like this:

Avatar URL:
https://mynextcloud.com/index.php/avatar/

Avatar URL Params:
/512

But 'Avatar URL Params' is prepared to be some kind of query string, not end of folder path. Query string always begin with '?', and script is adding it. So final URL passed to Discourse look like this:
https://mynextcloud.com/index.php/avatar/username?/512

Resolution seems to be simple. Just get rid of this '?' from script. If someone will really need it then he can write it himself in 'Avatar URL Params'.

The issue points to the Avatar URL and Avatar URL Params configuration and the script that assembles the Discourse avatar URL. Start by tracing that URL construction, then verify the resulting Nextcloud avatar path when a path suffix is supplied. Done means the generated URL uses the configured suffix without inserting an extra question mark.