[ks1723]

Quote from one of the authors:

“A microwave is not a pure, pristine place,” Porcar says. It’s also not a pathogenic reservoir to be feared, he says. But he does recommend cleaning your kitchen microwave often — just as often as you would scrub your kitchen surfaces to eliminate potential bacteria. [1]

So I would not worry too much.

[1] from here: https://www.nature.com/articles/d41586-024-02553-9

[edit: added source link]