So where is bitter taste come from? I know it is not wet cigar.
Bitter taste can come from a lot of things. Given all your recent inquiries about humidity, I'm not convinced it's not wetness, as it takes a while for cigars to acclimate to a lower rH. If they were stored at 70% for a while it's going to take a month or even two months for them to drop down to say 65% or 62%. So it could be a wet cigar.
But it could also be that they're in a sick period. Or it might just be that they're in shock. Some cigars still go through a period where they just need to rest and acclimate. Transit times, recent sudden changes in temperature or humidity, etc can trigger bad times for a little while.
It could also be your smoking habits. If you smoke too fast, or draw too vigorously, that can also cause a burnt or acrid, or bitter flavor.
It could be you. Often times the food we eat, what we drink, even what medications we're taking, can affect our palate.
Or it could just be the cigar. The cigar might just be young and need some time to let the rough edges wear off. Different from a sick period, some young cigars just display rough characteristics that only age can wear off. It could also be that the tobacco was not cured properly and the cigar is just a dud.
There are tons of reasons why you could have a bitter experience. We need more information. How long have you owned the cigars, what cigar is it, how are you storing, what's changed, have you had good experiences before the bitter ones, was it the same stick from the same box, etc etc etc.