I'm not what there is to believe in mask effectiveness?
There are studies about it.
You don't get infected with COVID just because it's a mix of your own immune reaction, the amount of particles etc.
A mask is really easy to wear and reduces your risk.
I'm not advocating for mask mandates at this point or let's say I don't care about it but if you want to reduce the risk of having COVID while on holiday, I would suggest trying to wear a mask.
Independently of it, in Germany the hospitalization is currently high and plenty of personal is sick. I still don't want to be in a situation of having something really bad and having to be in a hospital right now.
Just be aware that it might mean for you that you catch COVID and will be sick in your holiday.
I got COVID from one event 3 weeks ago and it threw my plans around.
It wasn't that big of an issue as I have a booster but I planed to visit a close friend who does cancer treatment and I was quite happy that he had no time for a short visit as I learned about my COVID invection two days later and I don't want to put him on unnecessary risk.
Let's see and hope covids route to endemic is getting easier and easier.
There was and still are good reasons to be careful.
It would have been just stupid to get COVID out of yolo.
Now doctors have much more experience with it, vaccines exists.