Why this change? The traffic signals are still there, just turned off (when you did this change). They are actually enabled at this time. So it was never true that they were unrecoverably removed, which would justify tagging with 'was:'. 'disabled' and 'was' have different meaning. Yes, 'disabled' may be undocumented, which is another reason you should not touch it if you don't know what the original mapper meant.

You provide no source of your change so if you just did a random automatic edit without visiting the place, please refrain from doing such again.