I’ve been to Auschwitz, in case that makes any difference. It was a while ago and I don’t remember a cafe on the grounds, but the article says the cafe was close by. I doubt you’re supposed to eat or drink in there in case you spill anything?
I think a cafe is a cafe and if it’s shit you should be able to say so. If she’d said the horrible smoothie ruined her experience of the concentration camp then that’s different, but she just said the drinks were bad and expensive. She also didn’t post it on a Google review for the actual concentration camp, it was on her own TikTok.
But small cafes in or near attractions tend to be a bit rubbish. This is a very serious historical site, but it can’t be denied that it’s a tourist attraction. It’s to be expected that the offering will be basic (but drinkable, which it sounds like these drinks weren’t)