This is individual.
I felt significantly worse going that high even before keto. 80g was my safe limit. (It doesn’t mean I didn’t eat 20 slices of cake sometimes, I am me but it didn’t feel ideal. It just didn’t feel so bad so no regrets.)
Now? Sometimes it’s fine (still worse than staying very low), sometimes less so.
I’ve read stories from other people, experiences are all over the place. Some people can go back to high-carb and stay there as they just don’t feel bad. Some people gets sick for days after a single carby7 meal.
2 months? You probably got fat adapted already, at least you have that… It doesn’t go away quickly though I can’t say for sure it won’t… It didn’t in my case.
Weight gain? Some water weight gain is highly likely but that doesn’t matter, you lose it when you go back to ketosis.
If you overeat, fat gain makes sense too but it’s not true for everyone. And it’s only 3 days so it can’t be very serious unless you have some epic overeating skills without a body that quickens metabolism similarly epically when overeating.
I would worry about other things like triggering cravings or feeling worse. But these are quite individual. I never worried I wouldn’t come back soon, I knew it’s impossible to stay much higher-carb and my body is indulgent enough that I can’t get really unwell without serious effort while ignoring warning signs. I need to be more careful with sugars, though, especially alone.
Beware with lots of booze, keto is famous of drastically lowering one’s alcohol tolerance (and how amazing is that? cheap tipsiness! less good when you WANT to enjoy many beers I suppose).
Suddenly raising or gradually? No idea what works better for you. I handle a sudden raise pretty well and if I can choose NOT eating carbs before the inevitable, I do as that’s better for me. In my case, carbs add up. I have a hypothesis that I have some weekly carb limit and if I go over, problems happen. But I think I heard about people who had it differently…?