Look at the list bismp posted, and it's a quite fair assessment I think (with some exceptions, like Suarez in 2016)
of who was best individual player a season, and who the major contributor to the team or/and NT team with the greatest accomplishments
There you see how they switch criteria from year to year just to make an excuse to vote for their favorite player again (be it Messi for the Messi fanboys, be it CR for the CR fanboys)
Perfect example:
2018: Modric wins supposedly on the criterion of being major contributor to the success of RM and Croatia, and Salah (the best individual performer that season) misses out
2019: The criterion is flipped now, and the best individual performer (MEssi) of the season wins it, leaving out VVD, the major contributor of Liverpool's success
That's all you need to know about how they vote
The criteria is subjective, and the award itself said that it is just a guidelines that voters don't have to follow.
The voters themselves change on annual basis, and so is the award.
For example ballon dor was for 50 European journalists voting for best European player, then in the 90's best player in Europe (So copa was out of criteria for example) and then in 2007 became best player in the world.
Between 2010-2017 it joined FIFA and the award was voted by a journalist, NT coach, NT captain of each country. Then from 2018 it split and voted by a journalist from each country. And note that those journalists changes from year to year.
Then you have FIFA award, originally was done by coaches, then coaches and captains then join ballon as mentioned above, and after split they rebrand it to the "best" and it is voted by journalists, captains, coaches, fans with each contributing to 25% iirc (in general, I might be off in some details) and it was done by season then during covid became for calendar year.
All those changes drives some inconsistency, but it is normal and maybe even healthy inconsistency.
Add to that personal preferences, for example you see Salah as best player in 2018 but many think he wasn't performing as good as Messi.
There is also the weight of the trophy and presence of different ones. 2018 & 2019 had different winner for the top 3-4 tournaments (Liga, EPL, CL & WC)