When the sponsor is baked into the video itself, there’s no way for the advertiser to know how many of the people who watched the video, skipped past the sponsor. The only way they know wether their ads are working or not, is by seeing how many people used the discount code from said channel. If you’re the kind of person going thru the effort to install additional software on top of adblocker to get rid of this sponsored content aswell, I think it’s quite safe to assume you weren’t going to buy their product anyways.
Also if you’re still feeling bad about it, just donate few bucks directly to the content creator. That’s way more than they’re ever going to profit from you watching ads anyways.