I canned a ton of apple pie filling last fall - went and got some out and it has gotten watery, like the "gelled" part of the filling is separate from a watery liquid. Would this still be okay to use? The cans are sealed properly.
That is probably just moisture from the apples affecting everything. It should be fine.
Maybe as a test, warm the filling in a saucepan first, and see how it re-mixes together and if it gels again, if not, maybe add a bit of a cornstarch/water slurry to re-thicken, then bake with it.
I never can/freeze pie filling, I just do the fruit alone (or spiced) and add the thickener later once I have opened the can/freezer container and thawed the fruit. I never liked the mushiness I got when flour or cornstarch or other thickeners were in with the fruit for an extended period of time.
Good luck! I hate it when something I preserve goes wonky on me.