Why are so many backend jobs .net rather than Java?

I get it. .NET is great. I love working with it. But I'm a bit confused as to why it so totally dominates by local job market for backend/microservices/et. al given that Java has Spring, which is great.

FYI, my market is the UK.

Is there a reason for this? I know that Java is still more popular broadly than C# according to:

https://www.tiobe.com/tiobe-index/

Does anyone have data indicating that Europe/UK buck this trend of Java being more popular?