XF 2.2 Avatar issue - Style related? XF base? Addons?

[Frode789]

Checking my website to see if my images follows "good practise" and reveal errors, using RespImageLint.
There I noticed the following issues for ANY pages that has avatar images:

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The issue is also present on the default XF style on my forum.
Anyone seen anything similar? Anyone know what might cause this/how to solve it?

 

[Old Nick]

Avatars, XFMG thumbnails in widget, Resource thumbnails in widget, all checks passed:

 

[Frode789]

Yeah definitely something weird specific to my site..

EDIT: I found the bug. It is caused by @Ozzy47 XFOptimize...