Each pixel of the logo eather is fully transparrent or fully solid with black background.

I see that you have fixed this in 1.18 and I understand it if you don't want to apply those fixes to older versions. So here is the point: I don't know how to build this project or rather I don't know how to fix these exceptions. I would fix this issue for the 1.16.5 version myself but I don't even come to this point. I do know Java.
Forge crashes in the early build process with a MethodNotFoundException or "invalid bare key: ${modid}". So it should be a problem with the Java version. I tried with Java 8 231 and Java 17. This is frustrating :(
debug.log
Edit: I fixed it with replacing all ${modid} with packmenu and using Java 8 271

${modid}'s will be replaced on build, to ensure they exist to run in dev you just need to run gradlew processResources before first launch, and 1.16.5 does require java 8 (though I suppose you've figured that out).

Anyhow 1.16.5 is not supported, closing this.