Looks like older asbestos chimney, your comments.
Google “transite”. Is asbestos. Little danger if not friable.
The first pictures shows what may be cellulose insulation blown up against the chimney. It should be removed.
Looks like transite, probably manufactured at the Waukegan plant.
Asbestos & cement composition, but not considered to be a “contaminate.” However, if it is being used as a heat-vent for a fuel burning appliance, it should be replaced. A small, unnoticeable crack can allow heat to escape, which could be a fire hazard.
FWIW - Transite vents were originally manufactured and listed as B-type vents, which means they only required one-inch of clearance to combustible materials.
Has the UL seal of approval.
Approval of what?
And when was it “approved”?
UL is not an “approval” seal, it’s a marking that the vent (in this case, the coupling) has been “listed” for a specific purpose, based on the requirements set forth by Underwriters Laboratories.
FPE Stab-loc and Zinsco panels were UL listed also. Are you good with that?