Can you have both copper and aluminum feeding the same panel?
AL / CU feeder Lugs. Makes no nevermind but AWG must be considered.
Tarnish usually means power quality issues. Impedance overheating.
The feeder jacket looks blistered.
Sorry for the edit.
Looks like an old split-bus panel. It would not be typical to use two different wires like that but I don’t know of a rule against it. The aluminum wire would have to be a size larger than the copper to match amp rating.
The nylon jacket have deformed due to the bending. No issue.
As long as the lugs are rated for the conductor material and sized appropriately there’s no issue being mixed. It would be if the conductors were paralleled.
I see two copper conductors not aluminum.
The conductor on the right is tinned copper and to me it does not appear to be loose or show any signs of heat. Just looks like the tin is somewhat tarnished from age.
Agree on the tinned copper based on the insulation.