I'm still using the iPhone SE (2016) as my daily driver. I find overall it's fine, only occasionally does a button get cut off by the screen size with no recourse.

I’ve been confused by the “share” window where the screen dimensions cut content off perfectly, and there is no scroll indicator, so you don’t realize there’s more to the UI.

GDPR "consent" popups are sometimes not usable on the first gen SE, because some of them position: absolute with a fixed size that's larger than the screen. Coincidentally, the "Accept all" button is always reachable, with the "Settings" or "Deny most" button conveniently located below the unreachable fold.

I just read most stuff on Firefox Reader mode. No way to click those popupas cleanly on my phone.

Or Facebook photo preview where it cuts off the bottom until you open it to full, and no indicator it’s cut off except your own experience with crappy cutoffs. That often changes the meaning of pictures/memes.

Just a few times a button has been unreachable because of this.

Hasn’t happened with the iPhone 12 mini yet, but, it is a markedly larger phone with a significantly larger screen.

Same here, my iPhone SE (2016) is still going strong and I can't remember the last time I stumbled upon an app that gave me enough sizing issues to become frustrating. What I would've given for the 2020 SE to be the same size as the 2016, being able to do everything on my phone one-handed is such a nice perk.