my fiddles leaves are getting all crispy😭

This seems to happen every year and I’m not sure how to help it. I noticed the bottom leaves start to crisp up within the last month or two. I water ir probably every 6-12 weeks depending on soil dryness and it was thriving all summer, every single leaf on here is new growth from the summer because I chopped it down to a stump in March.

I have it in front of the patio window in the second slide, it’s the only bright direct light window in my apartment. It was originally where the rubber tree is but I moved it to the left in case cold drafts from the patio door was causing the problem. I live in Midwest Canada so it can get dry in the winter months, maybe that’s it?? I’m also worried the electric heat vents on the bottom there might be a culprit, has anybody had an issue with those damaging their plants? The temperatures and sunlight hours have dropped significantly in the last month so maybe it’s just throwing a fit over that??

I just want to do what I can to help it survive the winter with minimal leaf drop because I worked so hard to help it get to where it is now, I don’t want to start over again.