Hi @Confuserix,
I can’t confirm this in general.
I know of many websites where subdomains or third-party domains are tracked with Matomo without browsers blocking the tracker.
It could of course be that there are HTTP header parameters on your websites that tell the browser that only certain domains are allowed to run scripts.
This is typically implemented with the HTTP header “Content-Security-Policy”:
I’m not a web admin to give you precise advice here. However, I do know that if the header is present, you have to configure it precisely for all types of scripts, objects or frames and domains.
If a browser blocks because of this, you usually get a message on the browser developer console.