That is only partially true. If you continued using the same hero then it went back into season 33 wearing everything from season 33 plus any regular season gear that you put on it . You ended up with a way overpowered hero without gold, gems, or completed altar.
You lost the ability to use the best gear in regular season right away. And you had to spend an enormous amount of time trying to rework the altar.
If you rolled back your hero to the 3rd of January like I did then everything was restored minus a couple days of play time on your Seasonal hero.
After hours of sweating and attempting to rebuild my seasonal hero I finally gave up and rolled back my account…and was it ever a relief to have my girl back!