As a general rule, if you were living in Germany before in the specified sense, but were absent from Germany at the turn of the year in 2020 or 2021, this is harmless for your rights:

• Persons who had not yet lived in Germany for five years may be temporarily absent for a maximum of six months per year, or in certain exceptional cases up to 12 months without this leading to the assumption that they no longer "live" in Germany
• Anyone who had already been living in Germany for five years may have been absent from Germany for as long as five years without this resulting in the loss of rights deriving from the Withdrawal Agreement.