Pros:
you will have support
you could probably lift heavier in the gym
Cons:
its false support
doesn't actually fix the weakness
actually widens the margin of strength and natural stability
you may reinjure yourself even with a belt on because of your strength increases and confident increases in weight lifted.
what does your current ab and lower back routine look like?
how flexible are you in your lower body and lower back?
there is a way to lift beltless ALWAYS, but it takes some specific work to strengthen your core. its extra work, but makes it so you don't injure yourself picking up a box wrong, sneezing at the wrong angle or something silly like that. trust me, when your core is detrained, it happens easy.