Ex-Secret Number member Denise covers Day6 "You Were Beautiful" for her fans

One of the the best vocalists of this gen and she's gone after one comeback

Yes, "artist's artist" sphere for sure! What's good about Day6 besides a sort of timelessness is some of their music has a level of "accessibility". Not as big of a risk of failure compared to covering "powerhouse" solo singers, but it's still there and you have to at least be able carry half a note decently or it's going to show you're really lacking basics.