"I2P network reliability is currently degraded due to a novel and persistent attack. Please be patient as we work on mitigations. If you have not yet updated to the latest release 2.5.0, please do so as it provides some defences."
For i2pd users, you can try building their latest from GitHub which may help.
Stormy is an understatement. Last I checked, I was sitting at 4% - though it bears noting that I'm running my I2P router on a Pi, so I2PD is a bit out of date for me