You were a resident of MN for all of 2020, and continue to be a MN resident until you take steps to change your status.
If you resided in MN, were a resident alien for US tax purposes prior to COVID, and intend to return to MN, then you remained a MN resident during your COVID-related absence.
From tne Minnesota Deportment of Revenue's Domicile (Residency) for Individuals:
“Domicile” is the place you intend to make your home permanently or for an indefinite period of time.
Once you establish your domicile in Minnesota, it continues until you take actions to change it. If you move out of Minnesota, but do not intend to permanently remain in another state or country, you continue to be a Minnesota resident.
