They changed the numbering scheme, so... no, there aren't. Version numbers are now year-based, but previously they were not.

Last year they unified all their OS version numbers to just match upcoming year.

macOS went from 15 to 26

iOS went from 18 to 26

watchOS went from 11 to 26

and so on

No, 26 is the successor of 15. They changed the numbering to year-based.