Put a gentle "Use Firefox" (or any other non-Chromium-based browser) message on your website. It doesn't have to be in-your-face, just something small.
I've taken my own advice and added it to my own website: https://geeklaunch.io/
(It only appears on Chromium-based browsers.)
We can slowly turn the tide, little by little.
Mozilla opposes this proposal because it contradicts our principles and vision for the Web. Any browser, server, or publisher that implements common standards is automatically part of the Web. ... Mechanisms that attempt to restrict these choices are harmful to the openness of the Web ecosystem and are not good for users.
The full response is here:
https://github.com/mozilla/standards-positions/issues/852#is...