Board Thread:Council of Arrowverse Wiki/@comment-9346948-20180119051714/@comment-24152851-20180119133227

Other DC wikis and wikipedia literally list red sunlight as a weakness for Kryptonians. So long as it reduces the combat ability, it should count.

In the context of our pages "weakness" doesn't literally mean "weaker than normal", it means something that can reduce their effectiveness which would include moving them from a superhuman state to a normal state.