It simply continues to print but when the carts are loaded it gives the warning that warranty on the printer is compromised. I have several now that are expired and heads out of warranty too. The printers work flawless though. If it becomes annoying you can do another trick, use a new cart and when it is say at 10 ML left fill it with the remains of an expired cart (same color preferred

. The counter will go down to 1 ML or Low but the printer will still function and empty the cart totally. I usually put that kind of carts on a scale to keep an eye on when I have to get new ones. 50 gram for the 130ML types is as low as I let it go. There are no issues though when they run dry like it can be an issue with Epsons.
I have used Chinese under the cover PCBs to intercept cart chip data. A pit*, within a month all kinds of errors. The same I have seen reported by someone who could only use 6 reset chips (of the 8 of the Z2100) on a Z3100 and I have my doubts about the 12 chip packages from Alibaba.