Discovered the problem while chatting with host tech support. The corresponding PHP files where empty! I FTP’d the merge PHP file, cache empty; refresh; it worked.
The site log page was empty too so maybe I should just FTP the admin files again?
----- [updated: 31Dec2022] MacOS: 10.15.7 (Catalina) Safari 14.1.2; Firefox 108.0.1 (64-bit); 108.0.1462.54 (Official build) (x86_64)
Alter-Drukarsh connections | The Garelick: 3.3.11b - PHP 8.0 FastCGI - mySQL 8.