My .NET Item was rejected twice, could anyone give me a hand

My .NET element was rejected twice, a soft rejection the first time it was submitted and a hard rejection the next time.
Here is attached the link to the zip file containing all submitted files except the source code.

What was the first message?

The first message was that the “.NET framework was no longer supported”

Did you change the framework?

Yes, I updated it to version 4.7.2

It is currently supported, and it is the last one supported by my IDE