- as you mentioned, lack of spaces
- red letters on black background - I think it's common for them
- such a way of depicting a Cross - putting it in frames
I don't have any proofs that it is real from Old-believer tradition, and not f.e. made by Great Schema Monk instead. These features colligates to me with an Old -believer culture. That's all. Maybe Hopeful Faithful should look into it?