I try to share with you all my experience.
I got the printer about 1 month ago.. it worked good, I used the bed without any cleaning, and my prints were perfect.
I tried to upgrade to the last firmware but I was not able.. so I installed the community firmware.
I cannot say if it is exactly after the new firmware, or after some bed cleaning (soap and water, never used alchool)... my prints did not stick to the bed anymore.
I tried more or less everything, nothing worked. Then I made a new test: I userd the glass bad of my ender 3, that I cleaned with alchool. The prints stick perfectly (probably too much).
But honestly as I told.. I am not 100% sure it is NOT a firmware-related issue. But I do not want to go back and forth...
Please share with me your experience!