Ok, this is a weird issue which I have never experimented until now and because english is not my mother tongue, I don't know how to search it on the internet.
I tried the example given by the RTCLib library. I set the time and date of the system and arduino show it ok on the serial monitor.
I disconnected the rtc (always with a battery. New battery cr2032 3v). After a few hours, I connected it again and I checked the time. it gives me the correct date (today) but hour and minutes are the same as the time I connected first.
So it keeps the time but not increment it, just keep the time it is saved.
Any idea? My rtc are tinyRTC from goodluckbuy but they worked fine in past. I have 3 of them and all with the same problem.