You don't say if you are using an auto level system but in general they are hopeless. I had much the same problem with the bed on my Ender 3 pro and after end less tests found that simply chucking away the magnetic bet and getting a piece of borosilicate glass bed, Just go for an aftermarket sheet of glass. On that stick or PEI or which ever surface works for you on to that. My favorite is a 1mm sheet of Tufnol ( Garalite in USA) but what you eventually use depends on the filaments you use. At least you will have flat surface to start with without that you haven't a hope.