My first layers bends on bed

I’m quite sure my bed is very even. I don’t use the standard magnetic bed top but have bought the special metal magnetic bed (forgot what it is called), am works quite well.

Recently I have noticed that my prints start to bend at bed level. See pictures.

Any suggestions on what can be wrong?

I have never had this problem before. Can it be because of heat not distributed evenly or something? It really annoys me