I’m running the bed that came with my Ender 3 pro (using a pei sheet, this is repeatable with glass too), been having this issue for a while I think. Is it time to replace the bed?
Update: Figured it out, what my bl touch was attached to was very loose, and was going up on the far side of the x gantry. and it’s now fine.
I got a glass bed then and simply put’ it on the stock bed. Takes 5 degrees more heat and a little longer to heat up but I am very happy with it. Btw, when you are at it: I would isolate the bottom side of the bed to conserve energy. You can buy ready made isolations with a glue- and an aluminium side.