You're (possibly unintentionally) distorting/diverting the issue. Nobody is criticizing open source maintainers for trying to get funding in an abstract sense. (We can all agree open source maintainers need income.) However, if the concrete implementation of trying to get money is unwanted and unexpected ads, then the correct focus of discussion is the criticism of that ad delivery method. The succinct version of this is: "The ends do _not_ justify the means."
As hypothetical examples...
- If Pi-Hole maintainers get the "clever" idea to get funding by changing "doubleclick.net" from returning "127.0.0.1" to the ip address for "BuyPiholeTShirts.com", people are going to criticize that "ad". It doesn't matter if Pi-Hole volunteers "deserve" more money, the correct focus of criticism/discussion is the sneaky ip redirect.
- If the maintainer of d3 Javascript library (https://github.com/d3/d3) decides to embed advertising such as "Try LINODE for 30 days!" in "README.md" and inside the source code comments of every js file, the correct focus of discussion is those ads and not whether the maintainer needs money.
The methods of soliciting funds do matter.
So far, socially acceptable ways seem to be Patreon, or getting hired by FAANG, or grants, etc. The "clever ideas" like NPM console ads are not socially acceptable.