I don't use the Spotlight icon... just [CMD]+[Space] to open up the Spotlight search bar, and have the icon hidden.
That said, "back in place" is misleading ... the issue is that placement of the Siri and Control Center icons are fixed... and cannot be moved... so you can move the Spotlight icon anywhere on the Menu bar EXCEPT the first two (right-most) positions. I tested it, even without the Siri icon being displayed, and I could not move the Spotlight icon (or any icon) to the right of the Control Center icon, regardless of what icons are displayer or hidden.
Also, under Big Sur, you can hide all of the icons except the Control Center... so I have hidden both Spotlight and Siri.
Here's what my Menu Bar looks like:
View attachment 1685365