Agree with all the others who have helped....
Potted figs seem to cast off leaves frequently, and I'm in the exact zone as you are, and have one in the ground. Mine is a 'chicago hardy' and it is hardy in zone 7, in a protected spot near a fence, and drought tolerant. Its 12+ years old, and about 8 feet tall and just as wide. And, very productive.
If you don't know the type of fig, yours may not be hardy in your area.
But, yeah... I've made lots of cuttings, and many have leaves like yours right now.
Are they pot-bound? Sure!
Here's the proof!
They all need to be up-potted into bigger pots. Figs have really robust roots. I root-trim them a little when I pot if they look like this, and try to spread out the roots in the bigger pot. Sometimes I cheat, and just do the root-trimming and slip it back in the same pot- but it's a non-judgmental thread here, right? (and I've got extras if one succumbs- you don't.)
Winterizing. It's getting late in the summer for fertilizing if it will be going dormant. You could fertilize now lightly, but don't wait any longer. The plant needs to start winding down it's growth to prepare for dormancy. I start to lesson the water as well. If you'll be growing it indoors, that fertilizer timing may not matter.
If trying to leave it outside, remember that it won't be as hardy in a pot as in the ground. I let my potted figs get the first few frosts, and then give them a few more weeks outside- which will strip all the leaves and bring them into 'soft' dormancy. Before the real winter hits, which would be hard dormancy (or maybe death,) I take the pot into an unheated garage to over-winter without light or water.
The in-ground fig gets no protection.
Good luck with that fig!
And, wear gloves!
