Deprecate light

BUR #410 has been rejected.

deprecate light
deprecate lights

Both tags are awfully ambiguous, and that since it's basically leftovers from Danbooru where it has already been deprecated over there, I see no reason to keep it, especially since we can just tag the light source instead.

Before you made that BUR on Danbooru the same deprecation was proposed and rejected almost two years prior. I'll say again what I said there: deprecating these tags just means the concept won't be tagged at all, especially given the much lower activity on this site meaning people aren't going to bother trying to fix the errors or ask for helping tagging something.

This bulk update request is pending automatic rejection in 5 days.

This bulk update request has been rejected because it was not approved within 45 days.

The bulk update request #410 (forum #2752) has been rejected by @DanbooruBot.