Sometimes we slowly increase caloric intake without us noticing. Slightly larger portion sizes, increased snacking, etc..
IF doesn’t do any magic tricks regarding weight loss when your caloric intake is not below your caloric needs.
Do you live a place with winter and activities dropped? People tend to lower their activities in winter and increase their food intake with things like the holidays if that is you. So if this is actual weight increase then you likely are above your caloric requirements. And remember it might not take much. If all 5 pounds was fat added that is only a 200 calorie a day above your TDEE over 3 months. Pretty easy to drop 100 calories in less needs because of reduced activity and add 100 calories in food.
Do you track the number of calories you consume each day? I think the issue may be with your weight loss diet. I don’t even exercise, but I still lost weight by following a diet.
I have the same problem as you, I am also an overweight person. I choose to build a diet plan to weight loss. As far as I know, diet for more than 70% of weight loss. Then I found this guy on Fiverr. He gave me advice and helped me build a diet plan. Since following that, I lost 9 pounds already.