Thanks for the answer @saoiray then we will have to wait for the answer from @fanboynz if you can remove closing advertising because it is too annoying when you want to reload the page and it appears like that again successively.
You are right something was missing! It is still a normal custom filters, nothing fancy, like when I was trying to use scriptlet from uBo Scriptlets to ‘call’ the function, so I was doing it like radioagricultura.cl##+js(callfunction, close_welcome_ad, 0) and let the function do the same that can be done with custom filters can do.
But it is just BS ads, not like anti-adblock or anything, so it was easy.
The thing was that it is calling a function when you hit the close button from the popup, funcion called close_welcome_ad, which you can go to devtools and run close_welcome_ad(); and it will close the ad like when you click on the X button, because it is pretty much doing a ‘when you click on the close button, then run this function’, which will hide the welcome-ad (exactly what the cosmetic I gave does), but also it will add a css property overflow: visible to the body, so this is what was missing to scroll the page.
I just had to read what it was using, but I checked thanks to you.