Yes I’ve been testing this and am seeing a similar issue with my Series 10.
From my testing, 99% of the time it’s right after I’ve taken the watch off the charging cable and placed it back on my wrist.
I enter my PIN which unlocks the watch, rotate my wrist back to a resting position and when I rotate it back to look at the watch face it’s locked again. This will happen over and over, sometimes up to 10 times and then all of a sudden it’s happy and works fine.
It remains connected all night long and into the next day, until I come to charge it again and then I hit the “PIN loop”
Watch is on my left wrist which does have a tattoo under it, but as I’ve stated it works fine unless I’ve just removed it from charging.