UPDATE:
I've experimented with it now, and it looks like it works fine.
And I've just realized, you can test the fix yourself - simply open Options page / General / "Custom CSS styles:" and paste there this style:

html:not(.drag_and_drop, .add_current_mode, .edit_dial, .edit_group) {
.hide_dial_plus.dynamic > .dials > .is_plus:last-of-type {display: none}
}

/* ------------------------------------------ */

Hello,
I can confirm that the hidden "+" dial is indeed taking space.
I'm not sure why though.
But I understand how this is unexpected from the user point.
I'll do my best to fix this in the upcoming 27.2 version (it should be out in a few weeks).
Best Regards,
Juraj Mäsiar