(MobileFrontend has nothing to do with this page)

Same thing happens on other wikis, I checked.

FlaggedRevs wraps revision lines in a span element with a class: <span class="flaggedrevs-pending">, <span class="flaggedrevs-color-1">, etc.

This makes the following native rule idle:

.mw-changeslist-line-inner > *,
ul.mw-contributions-list li > * {
  float: left;
  margin-right: 0.5em;
}

With wrapper	Without wrapper

To reproduce,

1. make sure you have "Advanced mode" enabled at https://en.m.wikipedia.org/w/index.php?title=Special:MobileOptions;
2. go to https://en.m.wikipedia.org/w/index.php?title=October_15&action=history.

(FYI)

This is less bad with the 'new' mobile page history.

In T238885#9675315, @Jdlrobson wrote:

Suggested changes

With a single change this looks a lot better (see screenshot) :

• Move class onto li element and remove the span.

This single change causes regression on desktop (Vector-2022): the review status of the selected two revisions is not visible, because the selection CSS overrides the FlaggedRevs CSS. (It also causes that the whole line is yellow/blue on desktop rather than just the part containing text, but which one is better is a matter of taste. Loss of information isn’t.)

Before	After

This is occurring on anonymous page views too?
https://en.m.wikipedia.org/w/index.php?title=Paris&action=history
Can somebody please confirm?

If so, this is likely high/unbreak now IMO

As @Samwalton9-WMF noted in T238885#9658700, the rendering has significantly improved some time ago.

I don’t think it’s that broken that it would warrant UBN, but I do think there’s room for improvement even from the screenshots @Samwalton9-WMF shared. It’s not terrible, but not nice either.

In T238885#9714312, @Jdlrobson wrote:

This is occurring on anonymous page views too?

Yes, action=history of pages that have ever been reviewed (pending pages protected articles on enwiki, pretty much all pages on dewiki) shows the review status for all users – and has done so ever since I can remember.

In T238885#9700080, @Tacsipacsi wrote:

This single change causes regression on desktop (Vector-2022)

Maybe the change should only be done on Minerva? Like this:

--- a/includes/frontend/FlaggedRevsUIHooks.php
+++ b/includes/frontend/FlaggedRevsUIHooks.php
@@ -715,7 +715,17 @@ class FlaggedRevsUIHooks implements
                }
                # Style the row as needed
                if ( $class ) {
-                       $s = "<span class='$class'>$s</span>";
+                       if ( $history->getSkin()->getSkinName() === 'minerva' ) {
+                               // On Minerva: the history is more like a table, so color the “row”.
+                               // This also avoids introducing a new “cell” (the <span>). (T238885)
+                               $liClasses[] = $class;
+                       } else {
+                               // On other skins: the history is a list, and the background color of
+                               // the list item itself is already used to highlight entries selected
+                               // for comparison. To avoid clashing, color only a <span> within the
+                               // list item.
+                               $s = "<span class='$class'>$s</span>";
+                       }
                }
                # Add stable old version link
                if ( $link ) {

I've subtasked T387091: FlaggedRevs incorrectly causes icons to be displayed next to usernames & user-links to be hidden when viewing a page history on mobile (with AMC enabled), and have left a comment on that task with notes of some investigating I've done into it.