OK. It certainly looks from the dates and nature of the error that the problem arises from the CDN change, possibly HTTP/2 but maybe something more subtle.
I guess a curl probe every few seconds would show up the error sooner or later. Might it be load related (most of my accesses happen around 06:00 UK time, as they are in cron.daily and that seems to be the default run time on most Debian systems) so that’s +/- midnight in the US)?