I checked The Windows Interface Guidelines for Software Design (p. 381-382 for information on unavailable appearance for buttons), but it does not specifically say what the correct behavior is. Still, it seems like it will be more logical for a disabled button to not be "clickable" - especially as it will not perform any action.
On the https://jdan.github.io/98.css/ page, "disabled" buttons still can be "clicked" - they show their :active state.
I checked The Windows Interface Guidelines for Software Design (p. 381-382 for information on unavailable appearance for buttons), but it does not specifically say what the correct behavior is. Still, it seems like it will be more logical for a disabled button to not be "clickable" - especially as it will not perform any action.