The latest post-peak Perseid activity reported among 2018, 2020, and 2021 occurred in 2021.
The International Meteor Organization records high activity well after the main Perseid maximum in 2018, 2020, and 2021. The reports placed these episodes roughly 0.7 to 1.5 days after the main peak, showing that the shower can have notable structure beyond its central maximum.
These late increases are associated with Earth encountering separated dust trails or filaments within the broader stream. They should not be confused with the official maximum, which is the principal predicted peak used for standard observing forecasts.
The same forecast notes that nothing similar was observed in 2022–2024. That comparison illustrates the irregularity of fine structure in meteor streams and why each year’s observing results can differ.