As far as I know, trailing spaces have never been exported from translatewiki.net.
But this happened today with b0e39cb5c100bcf0f89f778cc4408e51236b5a2b and needs a revert with I42aa0820aa73e211e0362d6dd40b03d327a15caf by Bartosz (thanks).
The trailing space in the translation exists since 2023: https://translatewiki.net/w/i.php?title=MediaWiki:Discussiontools-emptystate-desc-self-temp/se&action=history
Maybe related: T260187
The trailing spaces in this case are actually non-breaking spaces (MediaWiki would have removed normal spaces).
They have always been exported, but last week a different bot removed them from the JSON files: https://gerrit.wikimedia.org/r/c/mediawiki/extensions/DiscussionTools/+/1029837
There's also this task about this problem: T364727: Banana checker should not block CI on issues with translated content
@Raymond Did you process these changes or someone else, or did they not show up at all?
@matmarex removed the non-breaking space from the translation so that the next export was OK.
When writing this task I was not aware that a non-breaking space was the issue.
The fact that they are NBSPs is highlighted in the Phabricator diff, but not in the Gerrit diff (which is normally what people look at). Maybe some functionality to highlight NBSP and other (near-)invisible characters (LRM/RLM etc) could be added to Gerrit somehow?
I guess I have ignored these changes with the next sync because I thought, that were changes made by our translators in the meantime that should not be overwritten. That's the reason why translation changes via Gerrit are not welcome. I have never seen changes by Libraryupgrader before.