I'm not sure whether it exists in previous released versions or not, but this is the first time that I'm sure this problem exists.
Running vanilla server. world is created before 1.11, and continuously upgrading to 1.16.1.

It generally took 5% CPU usage when no player is logged in, and about 15% when just a player is logged in(without movement that will cause chunk loading and unloading).

With the help of 'forceload' command, a single chunk(actually 3*3) is loaded while no player online would take up about 75% and will burst up to 115% for a short shot. When there is a player online, java process will always eat up the whole CPU core.

Without 'forceload' command, it is also possible to keep the chunk loaded by throwing items through nether portal. When 5*5 chunks are loaded by one portal maintainer, the process will always eat up a whole CPU core.

No comparison data between different versions can be provided.