Unusual cable in subpanel

Anyone have an idea of what these cables are for? They are routed into a subpanel next to each other without cable clamps, crimped together, and not connected to anything within the panel. Panel is installed in a finished wall. House is 2 years old.

Since it’s an irreversible splice I would guess that it’s a grounding electrode conductor but more information is needed to confirm that.

Do you have a pic, with dead fronts off, from further back?

As I understand you, there id a service disconnect panel, and 2 remote distribution panels…correct?

That’s what I was thinking, Robert, a gec.

Main disconnect outside at meter. 1 remote dist. panel in garage.

Must be a GEC which is permitted to be spliced by irreversible means. Maybe it was originally run to the sub-panel and then extended to the service disconnect on the outside.

Thanks for your help, guys.