Keto allows sugar and carbs… Many people eat sugar and carbs on carnivore too, just even less than on keto. Little carbs can make a big difference sometimes.
What to do after you have met your goals? It depends on the person.
You can do low-carb, you can stay keto (it may be a way stricter version than previously) or you can do something else, whatever floats your boat.
To me, it’s odd if someone does keto, gets results, feels better - and goes back to high-carb. It doesn’t make much sense to me. If it’s suffering with great fat-loss for you but you chose to lose fat this miserable way, fine, go back to some carbier diet, keto isn’t for everyone. But not all carbs are the same either, try to eat more healthily. Even if you need much carbs, you don’t need added sugar or overprocessed stuff, all the tempting (not for me) overpriced bad-quality snacks… Eat normal food.
Slippery slope, I know that to some extent. That’s why I plan to stay close to carnivore on most days. It doesn’t matter if I reach my goals, I feel better this way. So if carbs causes problems for you, why do you want to go back to them?
I understand being curious but you can’t know how you will feel later. Maybe you will do keto for life, who knows? Or you will realize what your ideal, non-keto lifestyle should be.
People change. When I started keto out of desperation, I had no idea it will be longer term. I don’t do keto all the time but I never will abandon it for good and as time passes, my carb intake got smaller and it’s good. I thought it’s impossible for me to eat little vegetables (like, 20g net carbs or less for them, it was an uncomfortably tiny amount for me. I don’t eat most green leaves). Now I spend maybe 1g net carbs on vegetables on a normal day and I feel way better doing so… If anyone told me this just a year ago…
Just do it and change things if and when they aren’t right for you.