FIXED!!!
I found the fix! Thank the lord, because this was very annoying. (I'm using A50, not sure if this fix will work for S10 and A70).
You can re-enable the double-tap and lift to wake, you can even re-enable on body detection, fingerprints, trusted location and gear(smart watch, headphones etc) unlocking methods, because none of them are the issue.
The issue is Samsung decided to ship the phone with flip wallet automatic unlock enabled.
To fix it:
Go into settings -> scroll down to advanced features -> click accessories -> turn off automatically unlock on flip wallet.
I have not had the issue since I changed this setting, I have double tap to wake and lift to wake both enabled. I have face detection on. I even have smart-lock on for my galaxy watch and a trusted location.
I am not using finger scan(too slow) or on body detection(don't need it, nor do I trust it), but have also tested them and they work fine after this change.
This single handedly fixed the issue for me after weeks of searching the web and trying different settings. So thank you Samsung for shipping the device with an obscure setting that very few people will use enabled!
Cheers, please spread this so that others can find out.