Windows 11 - Why does the "Never combine taskbar icons" shifts grouping to the left part of the screen?

Question

I tried the new "Never combine taskbar icons" function. It works fine up to a point - up to about 18 items open (See first picture). As soon as I open more icons, the grouping of them shifts to the left part of the screen (see second and third picture).

Does anybody know if anything can be done about it or why it happens?

When overflowing taskbar (18 icons):

When opening another (>18 icons):

18 icons expanded view: