In what way are PowerShell and .NET related? Is the .NET SDK included in PowerShell? Or is the .NET runtime?

In the release notes of PowerShell 7.5, I read:

Update .NET SDK to 9.0.102 Older releases have similar notes.

Why is this note important to know? Older releases had a relationship with .NET 8, is PowerShell compiled with a specific .NET version? Is a specific .NET CLR included in PowerShell?