Scientists detect fastest-ever fast radio bursts, lasting just 10 millionths of a second

Astronomers aren't entirely sure what causes FRBs. There's evidence that at least some of the radio pulses come from magnetars, a type of dense neutron star with an extremely powerful magnetic field.
Here is a paper with evidence supporting a related source for repeater FRBs:

We analyse nearly 7,000 bursts reported in the literature for the three most active sources of FRB 20121102A, 20201124A, and 20220912A, and find the following characteristics that are universal in the three sources. A clear power-law signal of the correlation function is seen, extending to the typical burst duration (∼ 10 msec) towards shorter time intervals (Δt). The correlation function indicates that every single burst has about a 10–60 per cent chance of producing an aftershock at a rate decaying by a power law as ∝ (Δt)−p with p = 1.5–2.5, like the Omori–Utsu law of earthquakes. The correlated aftershock rate is stable regardless of source activity changes, and there is no correlation between emitted energy and Δt. We demonstrate that all these properties are quantitatively common to earthquakes, but different from solar flares in many aspects, by applying the same analysis method for the data on these phenomena. These results suggest that repeater FRBs are a phenomenon in which energy stored in rigid neutron star crusts is released by seismic activity.