[Bed Visualizer] Bed shows a strong slant

Ender 3 Pro, heavily modded, most relevant: BLTouch, yellow springs, glass bed + PEI. Self-compiled Marlin.

I've been having problems with Bed Visualizer showing a strong tilt in my bed, and resulting prints don't come out. I first manually level my bed (several cycles) then run BV. It ends like this and my manual level is now too far from the bed. Rinse and repeat. It was working fine before, and I fixed it once by doing a tramming tutorial, but now it's back. Any tips?

My plugin does nothing to the prints, it just sends the gcode that you tell it to send, and tries to graph the resultant mesh data reported by your firmware.

Then why is my bed changing? Do I need new springs? It doesn't seem to loosen in other situations. Maybe I'll manually poke it with BLTouch to check if that's somehow too hard(?)

So should I do manual level -> run mesh from printer & save -> verify with BV?

Gcode is I think the default which indeed doesn't appear to change anything:
M155 S30
G29 T
M155 S3

Before I had dual-z, I've had to readjust leveling frequently as well. And it all had to do with slanting X-axis, as it's supported only on one side.

Well, you convinced me, it's on order.

I measured the gantry and it's about 1mm difference (top of printer to top of gantry. Playing with the eccentric nuts, I can move it from 1-2 mm but can't get it zeroed. I thought I read you want it level before putting on dual Z? I don't really see how that's possible anyway because it will mess with settings putting it on. Anyway, here's hoping that helps!