Temporal evolution of the longitudinal magnetic field (B_l). Top: full time series of measurements between 2006 and 2020 with ESPaDOnS, Narval and SPIRou. The shape of the data points corresponds to the wavelength domain, optical (circles) or near-infrared (pluses), and the colour to the epoch in which the observations were performed. Bottom: SPIRou time series split in four epochs phase-folded according to Eq. (1). The least-square sine fit corresponding to Eq. (3) (Stibbs 1950), to assess the change in magnetic obliquity, is shown as dashed lines. The six ESPaDOnS observations taken in 2019 are plotted as pink circles.