In reply to Tom.

WP has become a ticking time bomb.

Hint: We use this plugin (with version_compare() line adjusted to our tested and appropriate WordPress branch per website) to allow manual core WordPress updates in backend with staying in same branch and getting security updates for time being without major changes to existing sites.

https://wordpress.org/support/topic/wordpress-4-9-10-update/#post-11309601

Many long existing sites where we use this plugin, will never be upgraded to FSE or block theme or similar due to various reasons.