I can't think of many situations where this would be used, but certainly in emergency situations it could be useful! As J.Nikola mentioned, this technique only really allows for the mask to be used as a mask or a bowl, not both. I have also tested several kinds of masks during a science experiment with some of my students and I can confirm that they are almost all very good at holding water/ another liquid.
The mask would of course have to be a fresh one in order to ensure that you are kept free from germs as much as possible when using as a bowl/cup and you would really have to have no other choice but to use the mask. If you are using soup, you'd be much better off keeping it in the original container that it came in, especially if you have heated it up in that way.
For water, I think i'd probably prefer to use my hands personally. Out in the wild though, if you had water purification tablets but no vessel to keep the water in then a mask could absolutely work wonders.
N95 masks are not cheap. If I happened to have an N95 mask and absolutely no other method of drinking water, I'd probably stand there for a while and ask myself how I got into that predicament haha!
This has definitely sparked my curiosity as to other uses of masks though! Thanks Darko!