Yes, I do.
Having said that, I have just tested the back up process again by disabling my network adblocker and removing all adblock plugins from one browser (safari). Unfortunately, the backup process was still timing out.
Aug 20 13:36:31 UnRAID nginx: 2021/08/20 13:36:31 [error] 8704#8704: *7537943 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.1.114, server: , request: "POST /webGui/include/Download.php HTTP/2.0", upstream: "fastcgi://unix:/var/run/php5-fpm.sock", host: "a189c36bfe0d768a7142e859974ff75f2fcf51ec.unraid.net", referrer: "https://a189c36bfe0d768a7142e859974ff75f2fcf51ec.unraid.net/Main/Flash?name=flash"
Not sure if it's related. I noticed "invalid API key" message from myServersError when I enabled web inspector on safari.