PHP 7.4 End of Life/Security Support End Date (community)

November 28, 2022.

Zend PHP 7.4 LTS End Date (with help from Zend)

December 2026.

If you're using Ubuntu + Virtualmin, I bet you they will not be ready for 22.04 upgrade before then. I wouldn't freak out anyway because I expect 3 more years of support for LTS anyway.