Subscribed to Youtube Music initially and later thought of upgrading to Premium, but the trial didn't gave 3 months like earlier, instead first month was free and next two months will be 30rs charged. Now realising first trial whichever plan we subscribe to is for 3 months but if we upgrade from Music to Premium then next two month Premium plan will be half charged i.e. Youtube Music free + Youtube Premium extra part charged. That's tricky thing and bad on customer part!
How they do calculation:
Youtube Music - 99rs free + Youtube Premium 129 charged = 129 - 99 = So 30rs charged next two months.
Good thing is, If we cancel, still we can have the free trial till end. Check highlighted part: