https://watchers.news/2021/08/15/unexpected-large-perseid-outburst-detected-on-august-14/ 
In 2018, visual observers reported a narrow peak of Perseid shower activity around solar longitude 140.95°, about ~30 hours after the traditional Perseid maximum, with a peak of about ZHR = 25 per hour above the normal Perseid activity of ZHR ~ 45 per hour at that time (Miskotte 2019).
In 2019, a similar peak was recorded by forward meteor scatter observations collected by the International Project for Radio Meteor Observation. That year, the outburst peaked at solar longitude 141.02° with a peak ZHR ~30 per hour above normal activity (Miskotte 2020a; 2020b).
"The cause of this outburst is currently unknown but is probably the result of an unknown filament of comet debris produced by comet 109P/Swift–Tuttle as it raced through the inner solar system many centuries ago," the International Meteor Organization (IMO) said
