Hi @manoahklaasse,
Updated:
I interpreted it completely wrong, the image dimensions are not missing, by “Specifying Image dimension” GTmetrix meant, to specify the required image size in <img> tag which is kind of very detailed thing to do, because displayed dimension varies with device width.
Smush doesn’t handles that, it’s totally out of offered functionality.
https://monosnap.com/file/MZlVAZfBPuMrpWDKnwS1ec59GDcpyI
Earlier Response:
Since I’m using WPSmush, some image dimensions have dissapeared, resulting in slower load speed
It’s highly unlikely that Smush did it, because it just tries to optimise images if it’s already there.
You can try using Regenerate Thumbnails, it might help you re-create the missing thumbnails.
Hope that helps
