Can’t help you with the bed levelling but there’s about a hundred threads on it here.
I suggest measuring the difference between the high and low areas of your bed and set your first layer height to that value or greater. Only way I got it to stop doing what you show. The SM2 bed is neither level nor flat.
Note that the “bed levelling fixes” included in the most recent firmware versions are kind of significant. The points being probed by the older firmware versions weren’t quite where the machine thought they were. It might be worth updating, if you haven’t already. (Or not, since the most recent firmware introduces New And Interesting Bugs in other areas.)
It likely wasnt sensing properly then, because the print sheet itself warps up (with the frame underneath it), and the prox sensor detects the spring steel in the print sheet. That’s how this particular system works.
Firmware version 1.12.2 contains the levelling fix and changed little else so doesn’t have any of the “Fixes” in 1.13.1 that seem to be causing lots of problems. I think people should at least use 1.12.2