Could it be an issue where our server's own firewall is slowing/blocking some of Cloudflare's IPs? If the server is not aware it's behind another reverse proxy, it will look like a lot of requests coming from a limited set of IPs, which could cause some protections to kick in.
Haven't experienced any issue from Switzerland, though we have our own Cloudflare nodes.
Nothing on https://www.cloudflarestatus.com/ would indicate a global issue.
You can try hitting https://discuss.flarum.org/cdn-cgi/trace to see where the requests are being routed through. If you copy the full output, remove/redact your IP before sharing. colo= indicates which Cloudflare node is being used. EDIT: we already see you're on FRA from the screenshot, so I don't think there will be much more in the trace output.
