We apologize for the instability of composr.app and appreciate your patience. We are working on the statistics addon and trying to find an optimal way to store and render data. Unfortunately, we have yet to find a solution that can handle the traffic (and therefore, tens of millions of statistical records) of composr.app. We're working hard on one.
All browsers support CSP's request-uri, but Firefox doesn't support the Reporting API which report-to depends on. It's been behind a flag for years, and now isn't even available behind a flag because the implementation is outdated (https://bugzilla.mozilla.org/show_bug.cgi?id=1775194).
I've disabled CSP reporting for regular users via https://gitlab.com/composr-foundation/composr/-/commit/65ec77311484d4404d1c9b143f6dbec2eac3fabc so to avoid console errors.
So makes sense to hold off on this.