The decrease in hash rate has nothing to do with confirmation time.
I dispute that. The hash rate does affect the speed of confirmations. Difficulty is adjusted to try and keep the average block time at 10 minutes.
If for whatever reason (fork?) 25+% of the network hash rate drops off suddenly then expect confirmations to be slower.
It is either bad luck currently on the block or improper fees when sending the transaction.
I agree with it being bad luck. The average time is 10 minutes but there are regularly blocks that take significantly longer (and shorter as well).