Why do FOSS projects (e.g. Linux kernel, Firefox, LibreOffice, KDE, MediaWiki) not accept crypto donations but prefer to use sites like PayPal?

Long-time user of Free and open-source software (FOSS) like Firefox and of the Debian Linux distribution, as well as a reader of Wikipedia (which uses MediaWiki free software), I really don't understand why these open source projects don't accept to be supported by crypto donations?

They prefer to use sites like PayPal (as we can see right now and like every year at the same time with Wikipedia) which do not fail to charge them a substantial commission—of 2.89% + $0.49 per transaction for business accounts and 1.99% + $0.49 for registered charities.

This is all the more incomprehensible since BTC and ETH, to name a few, are also open source projects.

The ecological argument is not even a thing for ETH since the merge, so why?