CLRVersion is not your .NET version. Anything .NET 4 and above (4, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2. 4.8) will show CLRVersion 4.0. Any .NET below that will show CLRVersion 2. (.NET 1.1 = CLRVersion 1.1; .NET 1.0 = CLRVersion 1.0)

https://docs.microsoft.com/en-us/dotnet/framework/migration-guide/versions-and-dependencies

Here’s how MS recommends you find your .NET version:
https://docs.microsoft.com/en-us/dotnet/framework/migration-guide/how-to-determine-which-versions-are-installed

@echo off
set “mycmd=powershell -ExecutionPolicy Bypass echo $psversiontable ^| find /i “CLRVersion””
for /f “tokens=2,3,4 delims=. ” %%a in (‘%mycmd%’) do set dotnetver=%%a.%%b.%%c
set “mycmd=%windir%Microsoft.NETFrameworkv%dotnetver%MSBuild.exe -version ^| find /i “Build””
for /f “tokens=6,7 delims= ” %%a in (‘%mycmd%’) do set dotnetver=%%a
echo %dotnetver%

You will get “CLRVersion” entry which is your installed .net Framework version.