For all with an uneven bed where Bambulab doent care to provide a new flat one, and who are located in Europe i found a cast alluminium bed for P1P and another for P1P/X1 printer.
Take a look here: Cast Aluminium Plate P1P
and here: Cast Alluminium Plate P1P/P1S/X1C
I have a P1P and got the second one. But I think, if you have a X1C and dont care about the Lidar, you can even use the first one on an X1C if you want to go cheaper.
Pictures:
On this plate is no magnetic sheet on top. The embeded magnets at the bottom are strong enough to hold the print plate on the top. In the first picture (top) is the protective plastic sheet still attached. It holds very strong on the stock magnetic sheet.
They are not cheap but reasonable priced, in my opinion.