You are introducing a change of “field” where https://en.wikipedia.org/wiki/Peter_principle talks only of skills from lower level position being insufficient for competency at higher level. No change of field in the standard definition. I’ve read about, heard, and used the PP for decades without any change of field or tech vs mgmt being required to use the phrase correctly. It may be that higher level management requires training in a different field from lower, but in many firms it does not exclude promotion from below. Some of the best CEOs confound the PP to rise from the ranks.

I think your comment falls into the same trap that Mozillas leadership probably fell into: Middle manager and top management are different, even if they look superficially the same. Not every good team lead or even department lead is a good fit for being part of a companies leadership.