Their bandcamp reads “were dumb”. If they were trying to say that they are the band Dumb then they improperly wrote “were” instead of the correct “we’re”. They could be simultaneously saying that they are the band Dumb but they are also dumb enough to know include the apostrophe. Or maybe the name is perfect and they made that mistake accidentally. OR it could be that the “were” is intentional and they’re using it in past tense, as to say that they were dumb but no longer are.