Erroneous word suggested by spell checker. Not in user dictionary.

A word that is obviously spelled wrong is not recognised by the spell checker, and even suggested as a correction for a similar word.

— In my case, the word "perzeptueller" (German for "perceptual") gets the red wavy underline.

— "perzgptueller" is suggested as a correction, which obviously is wrong.

— "perzgptueller", when typed in, is accepted by the spell checker, which obviously is wrong.

The – misspelled – suggested word is not in my user dictionaries (~/Library/Spelling). Accordingly, I cannot "Unlearn Spelling" in the context menu.

An anomaly?