Slow write on remonte.php and a lot of sleep in mariadb

You have an app called "files_trackdownloads` force enabled, which bypasses compatibility checks. It appears that app hasn’t been maintained for many years. The error you posted is from that app.

Same goes for the apporder app.

I suggest by starting with disabling those apps.

Can you also attempt the section from the support template that is labeled Web Browser that you left blank?