A sudden dramatic change and recovery of magneto-environment of a repeating fast radio burst

Fast radio bursts (FRBs) are millisecond-duration radio bursts with unidentified extra-galactic origin. Some FRBs exhibit mild magneto-ionic environmental variations, possibly attributed to plasma turbulence or binary configuration. We report an abrupt magneto-ionic variation of FRB 20220529, a repeating FRB from a disk galaxy at redshift $0.1839\pm 0.0001$. Initially, the Faraday rotation measure (RM) had a median of $17\mathrm{r}\mathrm{a}\mathrm{d}{\mathrm{m}}^{-2}$ and a scatter of $101\mathrm{r}\mathrm{a}\mathrm{d}{\mathrm{m}}^{-2}$ over 17 months. In December 2023, it jumped to $1977\pm 84\mathrm{r}\mathrm{a}\mathrm{d}{\mathrm{m}}^{-2}$, and returned to typical values within two weeks. This drastic RM variation suggests that a dense magnetized clump enters and exits the line of sight in week timescales. One plausible scenario invokes a coronal mass ejection from a companion star, while other scenarios invoking extreme turbulence or binary orbital motion are also possible.