Sets/Reps??

Been working out for about 1-2 months now and just switched from doing 3 sets 6-8 reps to 2 sets till failure(usually get around 10-14 reps depending on workout). After a few exercises, it is much harder to do reps, harder than it would be if I’m doing 3sets 6-8reps. Is this normal? Am i doing this wrong or right? It just feels different…