The AI might have encountered these symbols in training on some weird occult neo nazi forums or something

Unfortunately, the double koppa as a Nazi symbol is neither new or rare, esspecially relative to the fequency of other patterns of symbols. Seeing as LLMs just output common text, its unfortunately unsuprising that this would be among the results if limitted to symbols.

There's no way this should've gotten past multiple people, it's inexcusable

Thats the trick. Has GOG gone so far downhill that they publish unreviewed AI output, is it that the company hired a Nazi and put him in a global marketing role with zero oversight, or does the company have a more widespead Nazi problem?

None of the possibilities here are good, and the fact that the apology doesn't even try to address any of these seems even worse.