I was crating bug to GitHub, but thought that this could be know issue, after upgrade, so thats why added this question first... I did se you managed to do it fist, so I added information to there. I use tags, both 1.4.5 and 1.4.6 has this issue.
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Upload cover picture does not work when using subfolder · Issue #5631 · NodeBB/NodeBB
Uploaded cover picture path does not contain the relative_path.