[Mariana (OP)]

Al asked:

We have an older microwave oven.  Works great but. Interior ceiling is peeling.  Is this a concern or problem?

What do you think?

[alancalverd]

Not a problem, except that you may get paint flakes in your curry. The steel case provides the microwave protection, and like all mild steel, it gradually rusts and the purely decorative  paint flakes off! Commercial microwaves use unpainted stainless steel that can be cleaned with mild abrasives.