I didn’t like the new color on methods in VS 2019. I tried to find which color I should change. I didn’t find one but you can revert to the 2017 style by disabling Tools > Options > Text Editor > C# > Advanced > Use enhanced colors for C# and Basic.
Sadly this reverts all of the 2019 color enhancements back to 2017. If any one know which color controls the method only please drop me a line.
Anders Malmgren 
Tools => Options => Environment => Fonts and Colors => Show Settings for: Text Editor => find in display items: User Members – Methods
Thanks will have a look!