I have a table top fan amazon link to fan which is tripping the bathroom GFCI when I turn it off. I thought it would be more likely to trip when turning on.

I have done zero investigative work so far . The GFCI is over 10 yrs old, so that may be an issue. I also need to try the fan on another GFCI outlet to see if it trips.

Any other ideas on the cause? Thanks

When you turn the fan OFF you get a little spike in the waveform , for lack of a better description . This is normal . Replace the GFCI anyway . If it still trips , chunk the fan .

selogic covered it very well.

I hate GFCI outlets.

I used to have to replace them all periodically.

They seem to have a limited lifespan, but I live near the water.

I ripped them out and replaced them with a breaker in the panel.

It has not tripped once and outlasted all the outlet GFCIs.

Breakers are more expensive but buy once cry once.

Replace it with a standard outlet and swap out the breaker for a GFCI breaker

Try the fan in a different GFI. It is possible that the GFI is just doing it's job and there's a fault within the fan.