Nothing at all unethical about it. We're not obligated to spend even one second looking at ads. They sent us free stuff hoping we were going to notice the ads they bundled alongside it. We're not obligated to do that though. It's that simple.
You're not ethical for consuming while also automatically bypassing even the possibility of an ad impression. It's the impression that pays for the content. No impressions. No content.
Guess the content just isn't gonna be paid for then. Not my responsibility to make their silly business model work. My attention belongs to me. I decide what I pay attention to. They aren't entitled to it. Sending me free stuff doesn't entitle them to literally anything.
To consume the content without even considering ads makes it unethical.