Ya last time I also add some anti mould powder to those expensive oil sealant liaoUse this solution then paint over after 24 hours. Want to use bleach also can if you have.
https://nipponpaint.com.sg/product/anti-fungus-solution/
Try to open the window when you are not at home. My brother place also have black mold on ceiling because he never open the window and the neighbour above always on the aircon. After he open the window no more. no need to open window big big, just 5-10cm opening help a lot.
Your thirsty hippo solution even spam 20 pieces won't help with your mold problem, dare to chop on this.
Then top up with expensive paint also
Oil based is must since not new coat n then it’s VERY SMELLY
the ceiling really last longer than without the powder
don’t have black dots but yellowish n can have the small flies like booklices on the ceiling because their food on the ceiling
Ts don’t think abt hippo because it’s expensive in the long run n not going to solve yr issues of sleeping with the moulds n fungus
also watched some video said moulds can cause dementia wor
So don’t play play n underestimate power of spores