Delivery via IPv6 still seems more stringent. IPv4 now requires "authentication" as well where previously only IPv6 did. Last I checked Google didn't use DANE, preferring instead MTA-STS -- perhaps understandable for a giant web property.
There is a form and people you can talk to if the form doesn't work. The form should have been mentioned in the reject message but is at <https://senders.yahooinc.com/contact#sender-support-request> though you should first review their information, rules, etc, starting at <https://senders.yahooinc.com/>, and the mailop mailing list at <https://list.mailop.org/listinfo/mailop> is where you can ask for help if the former doesn't suffice that will often result in direct contact with someone at Yahoo! that can get things done or at least give knowledgeable advice.
PiHole doesn't block all ads though it might seem to for some, and DoH (aka Private DNS) will eventually obsolete it if the amount of lost revenue doesn't remain trivial (less than the cost of implemention in their product).
You wouldn't lose the content just the ability to share it, if I read it correctly, which is something I wouldn't normally want anyway. My backups are done with restic so Google can't tell what's present since it's encrypted.
Honestly, if you're keen to share something you shouldn't, it's pretty trivial to host it via https://rclone.org as an http server. The only person accessing it off of Google drive is the original owner and gdrive can't tell that it's being shared beyond that.
I dislike this, trend it seems, of putting the language in the URL -- the Accept-Language HTTP header should be used which can express weighted preferences. Mozilla does use the header but redirects to the language (and product) specific URL which is usually okay for me but bad for sharing (IMO, obviously). But, https://addons.mozilla.org/addon/downthemall/ "works".
