mypoint:
If there is a lot of work for compatibility with .net core 3.1, I suggest not supporting it first. And through the powershell command line support.

Q: Will YARP provide compatibility with .net core 3.1?
A:
You can use the .net core3.1 client to access YARP through the command line, after ssh, there is a powershell command line interface. This command line interface is compatible with any external calls such as win, linux, python, etc.

user app want add back end to YARP--->commandline--->ssh client---> ssh server--->
powershell YARP module (powershell 7.1 preview base .net core 5)
---> the static method of .net core 5 of YARP
powershell eg:
1 Add-Type -Path "d:\yarp.dll" or "/xxx/yarp.dll"
2[YARP]::add_urlrewrite('http://11/aa/bb','http://22/cc/dd')

in windows via：winrm client --->winrm server

If there is a lot of work for compatibility with .net core 3.1, I suggest not supporting it first.

So far almost every works, the main 5.0 improvements have been in performance. We'll see if we run into any roadblocks later on.

ok,3q