Yes, I think your second sentence is key. Auschwitz is, mind-bendingly, both the site of incomprehensible atrocities and also a major tourist attraction.
If you google 'things to do in Krakow', tours of Auschwitz that will pick you up from your hotel appear top of the list, along with horsedrawn tours of the Old Town and the salt mines -- in fact lots of cheery ads encourage you to do a combination day divided between Auschwitz and the salt mines in the same way as Tripadvisor suggests the London Eye and the Tower of London.
I have neither been to Auschwitz nor seen the TikTok, but it's clear the woman in question is viewing the cafe as a tourist attraction rip off, rather than an aspect adjacent to a memorial site that commemorates genocide.