Downstream non-gfci outlet needs to power a refrigerator
Defrost Cycle

As discussed in comments, this problem does not happen immediately but appears to be related to the defrost cycle - in one test it took 7 hours until the breaker tripped. Assuming this is the GFCI tripping, which appears to be the case though that hasn't been stated clearly, that points to one of two possible problems:


The defrost mechanism itself is leaking current somehow, causing an imbalance which trips the GFCI
Water from the defrost cycle leaks to someplace that causes a ground fault. Exactly the kind of thing that a GFCI is designed to protect against.


So the question becomes: Is this the beginning of a potentially dangerous fault, in which case the GFCI may have saved someone from serious, even fatal, electrocution, or is this truly a minor issue, possibly even a design flaw, where the electrical leakage is so small and so hidden that it would never actually present a danger.

As Harper frequently points out, GFCI trips on refrigerators generally have far more risk of causing food poisoning and/or loss of food due to undetected problems than they do of benefit by preventing electrocution. So if the situation really is "not a real problem, just poor design that leads to GFCI trips every defrost cycle but safe to use" then the solution is to wire up a refrigerator-only receptacle off the LINE side of the GFCI instead of the LOAD side.

If, on the other hand, this problem is actually a sign of a potentially dangerous situation - perhaps caused by damage during the 5 years that the refrigerator sat unused - then fixing the underlying problem is a much better course of action.

No random person on the internet can make this potential life-safety decision for you.

(If it were me, I'd see if I could isolate the components of the defrost circuit to see if there was repairable damage. But that's me. And it is likely a non-trivial project to do that.)