I would sincerely advice you to move on from placing ads like you been placing, because most of the time they’re clicked by mistake and the user has no real intent of signing up.
Also use Twitter or Instagram, to find big crypto accounts that do paid shoutouts, and try promoting your affiliate link out there.
Lastly if you have lots of funds you could try native ad network, and make a compelling image that people want to click and sign up under your link, this can work well if you understand how native ads promotion works.
I do not have a lot of capital to do this, I didn't want to spend hundreds of dollars just for one banner, that is why I went with just specific places and ordered ads for like a week so I would have my banner up for a week in a good place and that's it, instead of going around in multiple places and have many banners.
What I was trying to say is that I have been doing this for a while as well, probably few years now, I just had this sudden increase in people who click but less people who come in and stay, like I said from 1/5 rate to suddenly 1/20 rate but maybe I was just lucky with the previous ones, because from what thequin said he has 5% retention rate and that is where I am right now. I didn't even changed the places I put my ads up, so no idea why it changed so drastically, freebitco.in didn't changed anything neither, by all accounts everything has been literally same for the past 6 months, interesting.