Hard to gauge on the little information provided but I can say that I think the advice you were given is not just misguided but 100% bogus. Stalling the tractor 3 or 4 times would not bring up a check engine light. I have a 2019 L2501. It looks identical to your L3301, same size, same loader, just no DPF filter and little less powerful engine. I have about 80 hours on it. I have stalled it a handful of times and Ive never had any engine or warning lights. Ive worked my tractor hard as well - not abused it, but worked it hard. Ive been clearing woods with it for many of the 80 hours on it, so lots of big log lifting, pushing tree tops into piles, so lots of pushing the weight limit, spinning tires here and there, and occasionally lifting the tires off the ground from all the various loader positions you get into with lifting this kind of work. Ive also put an oversided disc harrow on it and disced in these wooded areas after clearing, This disc really works the tractor as its a lot to pull. Ive never had any lights or warnings. The tractor just keeps performing.
Has the tractor been abused? Anything that happened that could have perhaps caused some problems? Was it pushed too far in some project, was bad gas put in it or was something else done out of the ordinary like this that could perhaps clue one in on what might be going on? Or, have you been doing everything the same for 60 hours and it just randomly popped up? If that is the case, I just have a natural inclination to suspect something with the DPF