Should PHP 7.4 be the default build target?

[Stubbs]

When creating new commits the various tools that run over the code before a commit default to PHP 7.4 and cause the checks to fail because there are features in the code that PHP 7.4 doesn't support (Union types for example.

Also, PHP 7.4 has been end of life since 2022, is it really worth the effort to maintain compatability at the expense of new features?