<p>I am building a toolchanger CoreXY 3D printer. I am in big trouble to find mic-6 aluminium toolplate in my country. Can you suggest me an alternative to mic-6? In my country, I can find easily 5083, 6082, 7005, etc. I don't think, that theese aluminium plates are suitable as heated bed. The design of the bed is the same as the <a href="https://jubilee3d.com/index.php?title=Main_Page" rel="nofollow noreferrer">jubilee 3D printer</a>, so it will be best to have minimum warpage.</p>

This is probably caused by too few top layers in combination with a too low infill percentage. Increase skin layers and increase infill percentage.
If you have multiple layers already (at least about 4 for 0.2 mm layer height, for smaller layer heights even more), you might be printing at a too high temperature and or too few part cooling percentage and a too low infill percentage.