Oh, the irony!
This has been coming for years, and there's no doubt that all browsers are in a battle.
If we simply wear the AdSense hat, this is a really bad situation.
Note, although the question is squarely aimed at FF, is not the only browser helping drive down earnings.
If we wear the Advertisers hat, this is really bad as it means we can't get to a significant audience.
For Google, it's potential disaster.
The whole thing of an advertiser-supported site is at risk, and It's why the IAB is trying to work out a way to get over this through, in part, the ad.txt program
How can this help? I wonder if there will be some kind of agreement made which allows ads.txt-compliance to browsers.
Many sites wont' allow you access to the content unless you accept ads from them. That's much easier when it's a major publishers, but if you're a smaller publisher you're less likely to get authorized.
Let me add, I really don't have a solution.