I'm running into this as well (Firefox Debian). I suspect it may be Firefox's tracker blocking combined with the older extended support release.
Sometimes just refreshing the page seems to work too. Disabling the tracker blocking allows cross-site requests to Cloudflare endpoints which seems to be enough. Maybe worth allow-listing CF domains, but I didn't look into if that is possible yet.
Sometimes just refreshing the page seems to work too. Disabling the tracker blocking allows cross-site requests to Cloudflare endpoints which seems to be enough. Maybe worth allow-listing CF domains, but I didn't look into if that is possible yet.