Well the flatter the better also as it warms up it might be changing even more of a gap the Bambu ABL can help with small amounts of changes but when it gets to big it will effect your layers.
Check out the post on Warp Beds
With petg you can set your first layer height to 0.24 or 0.28 to help for now.
Also you might see if your petg will work at these base speeds some of my petg I can push it even faster and keep the layer bond still good.
Tip: If you have not done it clean your carbon rods and adjust your x& y belts they will loosen up from when the printer was new.