As per Kevin Weekes:
https://twitter.com/user/status/1536033287738732544
Seems like a bit of a hasty move, though Brunette said a few weeks ago that he wasn't sure he wanted to continue in the head role. It'll be interesting to see what happens there.
It's a bit surprising considering all the success they had this past season and sure they were swept, but the team that swept them very well might win the Cup.
UPDATE: Paul Maurice named Panthers head coach (Brunette to stay on most likely).