MediaWiki 1.36.1 with Timeless skin.
Some RecentChanges table rows with long texts are overflowing/spanning outside their RecentChanges frame in (max-width: 850px) displays, so a "vacuum" of gray background of about 50 pixels appears aside of the webpage and beyond the content overflowing/spanning outside the frame.
You might want to try to reproduce that problem by creating a MediaWiki webpage with a "long" name and then view the change under RecentChanges in a display less than 850px viewport.
It seems to me that this problem can be solved with the following code but is it a good fix that won't cause a broader problem?
@media screen and (max-width: 850px) {
.mw-body table {display: contents}
}