This is a VERY GOOD QUESTION.
I also wanna know why it didn't change the .editorconfig when i change the severity at the light bulb.
1)) First of all, i'll will explain the 4 options.
It's like in Tools -> Options -> Text Editor -> Code Style - General
you'll see the 2 columns Preference and Severity,
the "Configure IDE0090 code style" should belong to the Preference column.
There're many code styles which i couldn't find in the GUI of VS 2022 (Tools -> Options -> Text Editor -> Code Style - General),
very inconvenient.
Luckily you can still configure them in the .editorconfig file.
I'm NOT 100% sure but i guess "None" means it'll completely ignore the IDE0090 .
"Silent" means you won't see a sign of the IDE0090 in the code, the only way is to move your mouse or the cursor (I don't remember) to the place in your code which triggers the IDE0090, then maybe a light bulb or screwdriver will pop up at the start of the code line.
"Suggestion" means you'll see little 3 dots in the code where IDE0090 is triggered.
"Warning" means you'll see green squiggle in the code, it'll still let you build, like any other warning.
"Error" means you'll see red squiggle in the code, it won't let you build, like any other error at build.
it might be fun to change them all to Error to spot them all then changing their severity to whichever we want,
i may try that in the future, please let me know how it'll be if you try it.
2)) About the stupid options that don't change the .editorconfig when we choose the severity options.
The way i handle it is to hover mouse over the option of severity that i want, then click the "Preview changes",
it'll show you the code that should be added into the .editorconfig ,
you copy that code then paste it into the .editorconfig like you saw in the "Preview changes" using something like Notepad.