According to https://stats.moodle.org/ the no. 1 version is use is Moodle 4.4 with 24%.
What is no. 2, what do you think? If you said 4.3, you're wrong. It is the 4.1 LTS with 18.3%.
And the surprise, 4.3 is not even no. 3, it has to share the third place with 3.11, both way behind with 8.4% resp. 8.5%.
So the "Your site is not up-to-date" scare in the version check is not bringing the expected results, eh?
I hope, 4.5 LTS will consolidate that, but unlikely do to do that in its 4.5(.0) release.