Hi @Fry1989, thanks for taking the time to report this and welcome to Wikimedia Phabricator!

Where to find New Zealand road sign W1-1.4a somewhere? Asking as https://commons.wikimedia.org/wiki/File:New_Zealand_road_sign_W1-1.4a does not exist... Where to find such a "tool" exactly? What are complete steps to reproduce?

I apologise, it is https://commons.wikimedia.org/wiki/File:New_Zealand_road_sign_W1-1.4a.svg. The file has the rename tool open on it as I put on a rename request hoping an admin or other user could correct the mistake, and when clicking on the link to perform the move, it still changes it to lower case. I wanted to link the actual tool/software main page but can not seem to find it. I am sorry that isn't helpful in this situation. I performed dozens of renames in the last few days and this only started to happen in the last 15 hours or so.

At the top of all files there should be a series of links including the discussion page, to edit, and file history. There should also be one to move the file name. I believe that option is open to all users to make requests, though only file movers and admins can perform the actual rename itself.

To replicate the issue, it may be beneficial to upload a temporary file to work with, and attempt to perform a rename on it. The new name should have a capitalised letter at the end of it, and when the rename is performed the tool will automatically change it to lower case.

To be clear: is this a problem with the Commons file moving gadget, https://commons.wikimedia.org/wiki/MediaWiki:Gadget-AjaxQuickDelete.js, or is it a problem with MediaWiki? You can bypass AjaxQuickDelete by opening the move link in a new tab. Problems with AjaxQuickDelete are not handled here, and should be reported to the gadget maintainers at https://commons.wikimedia.org/wiki/MediaWiki_talk:Gadget-AjaxQuickDelete.js or COM:VPT

I believe it is with the file moving gadget itself. If that is the case, then I will raise the issue on the dicussion page you mentioned. Thank you.