Vendor service fees?

Had a call with a vendor (in this case a compliance auditor) and when they got to the pricing part mentioned there was a 4% "service fee". When I asked about it they explained it as something that is pretty standard so they can "keep the lights on".

I've been on a lot of vendor calls for a lot of different products and services that your typical SaaS company needs and this is the first time I've encountered a service fee. Is this becoming the norm?