GFI plug keeps popping but it's weird

Garage plug popped on a hot day. Only thing plugged into that circuit is a freezer, and garage door opener.

Unplugged everything, still trips. Replaced plug, still trips.

I left everything unplugged and untouched. Next morning I can reset it and it works fine. Lasts for a few days.

Yesterday afternoon it popped again. Like before the next morning I could reset it fine. But then a couple hours later it pops again with nothing else plugged in.

Any ideas?