Do you have your service listed on fiverr or any other platform where i can find the review of your work as you know that youtube polices are very strict and they may spam your subscribers which is bad for the channel too.
Yeah I agree People like to see testimonials for your service, if you still don't have one you can send a trial in exchange for vouch or you send your official Fiverr services so we can check if you are offering a legit services.