Strange rule that's nowhere to be seen on the webs...

Strange rule that's nowhere to be seen on the website: you aren't allowed to wear your rucksack on your back, only on one shoulder or on your chest. This was only sprung on me (and everyone else, including people wearing very small rucksacks) when I arrived. I carry spare masks, extra sanitizer, and water in mine. I can't fathom why I can wear it on one shoulder but not both, but at least if I was forewarned I would have planned and brought another kind of bag. I like to spend a long time in front of different pieces and it is harder to do when encumbered.

Anyway, I might have dealt with it if I didn't see a pair of young men without masks at all walk through the gallery without being stopped by the guard. Indecipherable set of rules to me, and the only museum/public area I've been to since the pandemic (and I've been to a few) to create a problem for me.