Hard to say, but likely. "Reichsbürger" are the German monarchist an/or fascist version of the US Sovereign Citizens. Large parts of the far-right extremist scene are financed directly or indirectly by Russia, but a significant contribution comes as informant payments from the domestic intelligence services which have their own issues with far-right extremism. They did get some influx of new recruits during the Covid lockdowns, being mobilized again by (known) Russian financed right wing extremists.