They're a meme beyond discord as well, but not hugely mainstream, existing in a similar space to mentions of Ohio in a positive light. Just more Gen-Z ironic humor.
It's a take on "doth protest too much." Because Poland is super conservative, therefore secretly specialized in femboys.
These are all good questions. I don't use discord, I wasn't aware that this could be a thing either. My impressions of Poland come from other places....