Steps to reproduce:
1. Start a new project with the Universal 3D Core Template
2. Got to project settings and change the API compatibility is set to Net Framework and Editor compatibility is set to Net Standard.
3. Wait for the compilation to finish
Actual results: Notice the console errors:
Library\PackageCache\com.unity.render-pipelines.core\Editor\Lighting\ProbeVolume\ProbeGIBaking.Serialization.cs(329,25): error CS7069: Reference to type 'ReadOnlySpan<>' claims it is defined in 'mscorlib', but it could not be found
Expected results:
No console errors.
Reproducible with versions: 6000.0.4f1 to 6000.0.18f1
Not reproducible with versions: 6000.0.3f1 or older
Tested on (OS): Windows 11, Ubuntu 20.04. Cannot repro on Mac