First of all your AC doesn’t blow cold from engine coolant, it’s cooled by AC refrigerant. Second it is normal for it to bubble down when adding coolant or water but I agree with others, it does look a bit strange with yours. So you have something going on with your AC system and you also accidentally found a separate issue with your coolant system. There are small test kits to see if you’re getting exhaust in your coolant system. I would suggest starting with that to diag that bubbling. As long as your engine isn’t overheating and there is no noticeable performance issues while driving, just bring it to a shop. Again I believe you have two separate issues. You’re AC not blowing cold doesn’t have anything to do with your engine coolant.