From this line, I presume you are using Active Cloudflare caching, which means all traffic is being filtered through Cloudflare’s proxies. Plus as you can’t trace any blockage/timeout/errors in the webserver logs, my best guess is the telegram specific bot traffic could have been “blocked” by cloudflare itself. If you experience such issue again, you should quickly disable (grey out) the orange cloud on your domain and let all traffic pass through straight to your server and see if the site comes up fine.
Cloudflare can sometimes be really nasty, especially if you are running bots or other services that attract DDos attacks.
If the Services go down for domain on server level, you should raise limits / timeouts in the specific PHP-FPM config. Once you identify what settings work, better put them in the vhost template and apply that.
Good Luck