SendPayment has a FeeLimit field as part of the request that contains (fixed or fixed_msat) and (percent) values. SendPayment is also listed as depreciated and that SendPaymentV2 should be used instead. SendPaymentV2 does not have a FeeLimit field as part of the request, but instead has a fee_limit_sat or fee_limit_msat field and no fee_limit_percent.

I'm not sure why SendPayment is depreciated over SendPaymentV2 (I can't notice any meaningful differences) and I don't understand why the way fee limits are specified has changed, but we should still have the ability to specify the fee limit in terms of a percentage.