This is not exactly the bug of the document switcher

It is the bug only of the shortcut mapper for it.

I mean to say, when you change the shortcut key "Ctrl-Tab" of the document switcher
using the shortcut mapper, it only changes the shortcut key for the "entry point"
of the document switcher, but it does not change the in-built Ctrl-Tab shortcut key
inside the document switcher itself.

I mean to say, suppose, using shortcut mapper, you change the
shortcut key of the "Document Switcher"
from "Ctrl-Tab" to "Alt-CAPSLOCK" and
from "Ctrl-Shift-Tab" to "Alt-Shift-CAPSLOCK"

and then press "Alt-CAPSLOCK" to use the Document Switcher

then you find that after pressing "Alt-CAPLOCK" the "Document Switcher" strip comes at the center of the screen but it does not go away when you release "Alt-CAPLOCK". It does not go away using any key.

It ONLY goes away when you anyhow press "Ctrl-Tab" and then release it.