AH, on the same server : I reset a website from scratch and this time the Drupal install page gives : Internal Server Error The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator at [no address given] to inform them of the time this error occurred, and the actions you performed just before this error. More information about this error may be available in the server error log.
Only thing in the logs :
[Mon Apr 11 19:23:33.917186 2022] [fcgid:warn] [pid 19155:tid 140135018841856] [client xxx:8292] mod_fcgid: read data timeout in 31 seconds, referer: Select an installation profile | Drupal
[Mon Apr 11 19:23:33.917284 2022] [core:error] [pid 19155:tid 140135018841856] [client xxx:8292] End of script output before headers: install.php, referer: Select an installation profile | Drupal