I have noticed, that the icons in the lookups are not formatted properly.
Here is what I mean:
I have two custom entities. Both of them have icons in old and new vector format. All sizes are uploaded, but the Unified Interface is somehow misformatting them in the lookups. The picture here is for the regarding field.
In order to fix this, I was advised to try to modify the svg file like this:
The point is to decsrease the default size to 16x16 pixels. Then the formatting is fixed.
I did not notice any side effects in the other areas like sitemap of entity views, so I am sharing this tip with you.
Happy CRM day.