Selecting text

I can no longer select text on my iPhone. It’s been happening for over a month but I put it down to my old iPhone 6 SE, but just got a new iPhone 12 mini and the problem is on this one too.

Before you could tap and hold to get ‘select’ to appear over words on any app/notes/web page etc, but now it no longer works, or it’ll work 1 time in 50 after lots of random tapping. How can I fix this?