Ambassador / influencer agreements (I will not promote)

Quick question for people who work on marketing heavy start ups at an early stage - how exactly do you usually structure comp for ambassador / social media influencer agreements? I am creating a platform that WILL use promotional codes, so that is an option for me. Here are some questions: Flat fee OR % based on people who used their code or both? How does this compensation agreement change based on follower count / reach / etc. and how to reliably measure this and appropriately reflect this in the terms our agreement (making them more or less favorable)? Curious what it looks like on different platforms as well (tik tok, instagram, YouTube etc.) and how often they have to promote your stuff and how it's done? I'm just curious what the standard is for this type of stuff, and want to be very careful with how I form agreements at an early stage. Any other advice is very helpful as well!