Does this hotel have safety deposit boxes for valuables ?
I have been to this hotel twice and in my room I never had that, maybe at the reception but you should ask.
No they do not - stopped 4 times and never had one
Reception might have
( we just use a case with a tumble lock / not the same but keeps items out of view)
The hotel room that we had didn't have but If you send message to the hotel they will be able to advise as some rooms may have
Get an answer from Ibis Warszawa Stare Miasto - Old Town staff and past guests.