  PSR J1641+8049 is a 2 ms black widow pulsar with the 2.2 h orbital period
detected in the radio and $\gamma$-rays. We performed new phase-resolved
multi-band photometry of PSR J1641+8049 using the OSIRIS instrument at the Gran
Telescopio Canarias. The obtained data were analysed together with the new
radio-timing observations from the Canadian Hydrogen Intensity Mapping
Experiment (CHIME), the X-ray data from the Spectrum-RG/eROSITA all-sky survey,
and all available optical photometric observations. An updated timing solution
based on CHIME data is presented, which accounts for secular and periodic
modulations in pulse dispersion. The system parameters obtained through the
light curve analysis, including the distance to the source 4.6-4.8 kpc and the
orbital inclination 56-59 deg, are found to be consistent with previous
studies. However, the optical flux of the source at the maximum brightness
phase faded by a factor of $\sim$2 as compared to previous observations.
Nevertheless, the face of the J1641+8049 companion remains one of the most
heated (8000-9500 K) by a pulsar among the known black widow pulsars. We also
report a new estimation on the pulsar proper motion of $\approx$2 mas
yr$^{-1}$, which yields a spin down luminosity of $\approx$4.87$\times 10^{34}$
ergs s$^{-1}$ and a corresponding heating efficiency of the companion by the
pulsar of 0.3-0.7. The pulsar was not detected in X-rays implying its
X-ray-luminosity was <3 $\times$ 10$^{31}$ erg s$^{-1}$ at the date of
observations.
