Are these by any chance SVG images? I had that too. Mendix does not like an XML header anymore.
The link below is for native but this applies to any SVG image used anywhere in Mendix.
Opening the SVG in SVGOMG and saving it fixed the issue for me.
As this is a connector module, if this is the cause of the issue, the supplier of the module should supply optimized images.
it’s just a suggestion but,
If you have commitly regularly/daily, which is recommended, revert/branch to the last commit that was working.
Or delete the images and import them again. If you use the same names they will be recognized in the app.
or you can try re-rendering the PNG file, then it should work,
Hope it helps!