FW 3.13.3 - First layer is not as perfect in older FW versions  

FW 3.13.3 - First layer is not as perfect in older FW versions

Hello Prusa Enthusiasts,

due to some comments regarding the FW 3.13.2, I went back to 3.13.1 (including Full Factory Reset - thx to Karl-Herbert for his advice) and this worked well for me.
Now,  since a few days, the FW 3.13.3 is released and this should solve the reported problems (eg. layer shifts).
I flashed this version to both of my printers and it worked - BUT some strange things occured, which I have never seen before:

1. The first layer is by far not perfect. There are clearly visible deviations from left to  right - always on the lefthand side, I have -0.15 mm.
   This is repeatable and was not the case with older FW versions.
2. Unwanted color/filament change during a vase mode print. There was definetely no color change visible in the Prusa Slicer (2.7.2). I double checked it...
   Not repeatable by now.
3. During normal filament change (the old filament was out and the new was pushed into the extruder) the print head moved approx. 50 mm to the right.
   Not repeatable.
4. Accidental layer shifts in Y during (of course) a long print.
   Not repeatable and the print shows some nasty filament bloobs in advance to the shift. But this was not a print which is prone to trouble...

While writing these sentences, I remember that I had an issue right after flashing the first printer from 3.13.1 to 3.13.3.
After performing PID Cal, I tried to start the Thermal Model Calibration. This ends up with the message "FW crash detected...Debug data available". Even after switch off/on this message appeared in the LCD. 
As I was not in the mood to make a further "full factory reset"and I played around (long press on the rotary button)  and was able to move the Z-axis. After that the printer worked, see above.

Is this version so buggy and will a further "Full Factory Reset" solve these problems really???

I rolled back the FW to 3.11.0 (it was as well a suggestion of Karl-Herbert), disabled the FW check (to get rid of the annoying beeps) and made a separate first layer calibration, while the 3.11.0 did NOT have a valid "build in" FLC or 0.6 mm nozzles.

Regards Kassen