NC 19.0.0: This version of Nextcloud is not compatible with > PHP 7.2.<br/>You are currently running 7.3.14-1~deb10u1

AI don’t know whether Nextcloud 19 is really that far our of date, or whether it is just a bug, but either way, I shouldn’t be seeing this message when I try to run OCC, should I?

Hmmm. Am I the only person to hit this problem?

no, I also am

Webserver and CLI might use different php versions. php -v will tell you which one.

No, all are 7.3.14
In fact, they are all new builds that have never had anything before 7.3 installed.