Whenever I do a JavaScript exercise (not sure about other tracks, I’m a newbie) I have to go into my VSCode ESlint extension settings and turn off “Use Flat Config” file setting (because I use a flat config for all non-exercism related projects).
Now I just run this tool from ESlint with using an alias in BASH (see below) and everything still works fine (with my “Use Flat Config” option turned ON in the ESlint extension settings).
alias eslintmigrate='npx @eslint/migrate-config .eslintrc'