The purpose of a GFCI is to prevent electric shock to people. It trips when it detects stray current. To be exact, the hot wire current is not equal to the neutral wire current. It assumes the missing current may be traveling through a person.
Many things can leak current. Finding and fixing them can be a challenge.
If the GFCI that tripped is the shore power source, then anything in the RV could be the cause. Water heaters and electric heat elements in absorption refrigerators are often the cause.
If it is a branch circuit inside the RV then something connected to that circuit could be the cause. Unplug things to see if tripping stops.
Often current leaks are intermittent to start with and become worse as time passes. Water can make corroded connections leak and stop when they dry out.
Florescent lights can trip some GFCI devices.
On the other hand, GFCI devices are electronic and they can fail. Many owners replace them because they know how and it is cheap. Then they spend the time to track down the leak if that does not work.
Dutchman Kodiak Cub KD176RD 2018
Nissan Pathfinder 2015