I didn't lose a huge amount (1.5 stone) but I did/do find maintaining at goal weight somewhat difficult, probably not as difficult as losing the weight in the first place as ultimately you can afford to be a bit more flexible when maintaining, but it was a bit of a bummer to realise I couldn't just go back to eating whatever I wanted and no exercise and still stay slim. I did have a few blips as well, put on quite a few pounds and had to revert to weight loss mode for a while - actually I always find the last few llbs the hardest to lose and it takes a while so I could probably stay in 'weight loss' mode long term and not worry about ending up underweight, but that's just a bit too restrictive for me.
Basically I think whatever 'plan' or 'diet' you've been following to lose weight, you need to work out a moderated version for maintenance, and stick to it long-term. So for me I did 5:2 and now do 1 proper fasting day a week, plus stick to sensible, loosely calorie-counted eating in the week, eating a little below my TDEE to 'bank' some calories for more relaxed weekends. I also let myself go off plan completely for a few weeks a year on holidays and at christmas. I always, even on holiday, try to stick to healthy habits learnt from from 5:2 such as never snacking and eating in a 8 hour window daily to avoid evening munchies. I don't stick to it 100% of the time but probably 95% which seems (touch wood) to be enough to keep me within a few llbs of my goal weight, which allows for natural fluctuations etc.
I think all the major diet plans have suggested maintenance plans, so for MFP/calorie counting/WW/SW you can just increase your daily/weekly 'points' or calories limit, or with low carb you can slightly up your carb allowance... or if you could handle this psychologically, I've heard of people who have success with following their 'diet'/weight loss plan religiously in the week as for weight loss mode, and then eating whatever they want at the weekends but I think that would be too hard for me personally (Mondays are miserable enough as it is!). Plus also if you can keep going with or even increase exercise levels that will help too, but sadly at the end of the day I don't think there's any plan that allows unlimited gorging so you just need to find the 'least worst' option for you