> Well, how do you define main Linux distros? Isn’t the next smaller one not receiving the info always complaining?

For a first approximation: Ubuntu, Debian, RHEL(-derived) to begin with, and SuSE which is in EU/server space (AIUI):

* https://commandlinux.com/statistics/most-popular-linux-distr...

* https://commandlinux.com/statistics/linux-server-market-shar...

Seems like Gentoo, Arch, Mint, and Slackware could also be as well:

* https://distrowatch.com/dwres.php?resource=major

U/Deb/RHEL are 'upstream' of a lot of other projects, and fixes would trickle down to Rocky, Alma, etc. Perhaps VM OS in cloud (AWS, Azure) could be a usage gauge as well.