unexpected ] mark after undo/redo

[John Little]

Vim 8.2.106. After pasting lines with p, the ] mark is on the last line pasted. 

If I then undo and redo with u ctrl-r, the ] mark is now on the line below. I did not expect this.

The help says "Lowercase marks are restored when using undo and redo". 

Undoing and redoing the insertion of lines puts the ] mark on the last inserted line.

Am I missing something?

Regards, John Little