1997 Toyota Avalon, brake lights are coming on because the brake petal has lost some of its "spring"

The brake lights come on in the rear after i park the car. it appears the brake petal is not springing back for enough to disengage the brake lights.
it does not do this all the time, but seems to have start doing this at night when it gets colder. I can look outside and see my brake lights on, then go off, then come back on. It has made the battery go dead twice in the last week. is this a easy fix or something more complicated. this has nothing to do with parking brake, i normally do engage parking brake since i park on a flat surface road in front of my home.

More than likely, you just need to replace the brake light switch, which should be attached to the arm from which the brake pedal is suspended.

There should be a return spring for the brake pedal, maybe it broke.

On a '97 I’d bet VDC is right.
Get down with a good light and you’ll see the mechanism. It’s easy and affordable to replace.

You may also have bumped the switch out of adjustment. Simple to fix.

One more idea, less likely than the above so check those first, but one of the rubber brake hoses may be collapsing, preventing the brake fluid from returning.

Maybe a bit of oil on the pivot at the top of the arm, and the brake light switch can be adjusted a bit so it works right, too. If you aren’t up to doing it, any good mechanic or mechanically inclined and flexible person can.