What is a sensible refund cap for an AI?

We are about to enable AI refunds. Default cap is $30. Anyone running higher caps and not regretting it?

We run $50, single refund per order. Catches small returns and abandoned-cart credits. Zero abuse so far.

From talking to maybe 30 customers, $30 is the median, $50 is the high end before disputes pick up. Above $50 we always recommend a human in the loop.

Going with $40 as a compromise. Thanks.