A recent change (maybe [1]?) added a "Printable version" link to the toolbox on [[Special:Upload]].
Despite the fact, that is not useful at all there, it breaks the access key ("p") for the preview button which is added by custom JS to Special:Upload on many Wikis (e.g. [2],[3]).
The easiest option would probably be to not display the link there, similarly as it is not shown when editing an article.
[1] https://gerrit.wikimedia.org/r/#/c/62844/
[2] https://commons.wikimedia.org/wiki/MediaWiki:UploadForm.js
[3] https://de.wikipedia.org/wiki/MediaWiki:Onlyifuploading.js
Version: 1.23.0
Severity: minor