Steps to reproduce the issue

Joomla 4 admin
Media Manager

one way:

Drag 4 files from your desktop to drop in the media manager
Note they upload ok
Drag the same 4 files from your desktop to drop in the media manager
Note you get asked if you want to overwrite - say ok 4 times
note the huge blank space at the top of the page now

Another one way:

Select 4 items (holding down shift to multi select them)
Click delete
Click delete in warning popup
Note flashing as messages are added
Note blank space above "Item Deleted" message
Note that if you select 40 items then the space is then 10x the size

Video

Too large for Github. view here: https://screenshot.phil-taylor.com/2Nuj2Kgz

Expected result

Any messages should be shown
if there are 10 items deleted then message should say "10 items deleted" and not show 10 x "Item deleted"
"blank space" should not be there,

Actual result

As explained above.

screenshot with highlighted dragger the space to revel blank area divs:

System information (as much as possible)

Additional comments

In source, there are a messages in that "blank space" just not visible