Evolution of the polarized flux across the H_α emission line. The position angles (PA) are presented in red in the first row from day 2 (left) to day 6.7 (right) into the 2021 outburst. The PA on the 2nd day into the outburst (left column, top) shows a complex structure. The evolution of the polarized flux (in blue) and 0.01*flux (in orange) are presented in the second row. Asymmetries in the blue- and red-shifted peaks of the polarized flux are well visible. In the third row, the degree of polarization is presented.