We had the exact same issue explained by you for Sitecore 10.2 onpremon-prem. For us upgrading System.Diagnostics.DiagnosticSource.dllSystem.Diagnostics.DiagnosticSource.dll
from version 4.700.19.46124version 4.700.19.46124
to version 4.700.20.21406version 4.700.20.21406
fixed the issue. All Sitecron jobs are now running fine.
Using Sitecron version 3.4.0.0
Using Sitecron version 3.4.0.0
and Quartz version 3.2.4.0Quartz version 3.2.4.0
from the package. Thanks to my teammates Jothi and Parvathi for figuring this out.