I find that everytime inpress the power button in unlock the screen which puts the notifications in the banner and I can’t see them anymore.
I know it’s like a silly struggle, but on other phones I’ve had you can easily check your messages without unlocking the phone entirely.
Do you have fingerprint to unlock the phone?
That could be the issue in that case, it took me awhile before I understood this (coming from iOS).
Tap the button with a finger not scanned for fingerprint.
(I have a FP4 though)