Rust powder in A/C lines
While there is probably some rust in that junk, I would bet on a dessicant bag failure in that system.
The dryer needs to be replaced anyway, so cut it open & see if the dessicant has been spread through the system. It is sort of an orange color when new...
The lines can be cleaned, but it is a lot of work. Hopefully the TXV inlet screen kept the stuff out of the evaporator.
Does the suction line have the same contamination?
B.