How to find a client to advertise on my sites "monetize site"

I have several sites where I get a stable 2500-3000 users per day (US traffic), themed movies!
I used the adsterra partner network in recent years, but in the last 6 months they have dropped twice the payment!
I want to find a direct customer who would buy advertising from me! Ready to provide access to GA, etc ...

There are platforms that act as mediator but you will loose a lot.

try google ad and there are a lot of mediators platforms