Long story short. Was at firm A for 17 years, left because the team I was in was being repurposed and I didn't like the role and it wasn't my skill set. Left on good terms went to firm B, after two years they were purchased and I was tuped into firm C, been there 18 months and hate it. I would never have chosen to work there.
Now the team that was repurposed at firm A is being rebuilt because it was always obvious the new way was going to fail. Would you go back somewhere you had been before? I don't know if it would somehow look bad / like I'm undermining my own decision to leave in the first place?