Why do you assume they haven’t warned Mozilla in advance?
Also, Mozilla was fully aware that what they were doing is in breach of GDPR. I find it extremely hard to believe that the makers of Firefox are not fully familiarized with it by now.
Last but not least Mozilla is doing this for financial gain. It’s selling pur data to advertisers. Why should we excuse it? It’s a very hostile act.
If Mozilla has hit rock bottom and has been reduced to selling our data to survive then that’s that. We’ll find another way and another FOSS browser. Accepting it is not an option.
How do you avoid interaction if it’s being done automatically by your machine when you open up a print dialog, and if malicious servers can use the same names as legit printers?