That is quality, pricey Class I or Class II door hardware. It would be a crying shame to take a hacksaw to it. You didn't buy that from AliExpress... you probably got that from a competent vendor who gives support. Use the support!
You aligned your strike incorrectly
The strike, or strike plate, is the rectangular hole in the door jamb that the latch goes into.
You are supposed to align your strike plate so that thing won't fall into the hole.
As Moshe Katz deduced, it is exactly a dead-latch or anti-shim feature. When you close the door, this pice does not fall into the hole and is pushed inward.
When pushed inward, it locks the latch so it can't be pushed inward freely, e.g. by a credit card or screwdriver attack.
But try it. Jab on the latch and see how it retracts freely. Then hold down the dead latch and jab again. Doesn't retract freely anymore!
However, when the dead latch is pushed inward, the latch will still operate if actuated by the knob, lever or push bar.
Now, on the simpler dead latches like in Moshe Katz's photo, it has a reasonable failure mode if the latch is misaligned: the dead latch pin will retract with the latch. This one may not be like that.