Agologies for being late to this thread and for maybe covering things that have already been answered.A carbon frame as long as it’s been cured and moulded correctly is basically an inert object and untroubled by most temperatures [super high temp can delaminate the layers but you’re needing to blast it with a heat gun etc],the vast majority of longevity issues are issues to do with the post-moulding bonding of what are normally alloy parts such as dropouts/bottom bracket shells and cable guides etc .This is usually referred to as ‘galvanic corrosion’ on forums such as this ,it’s an ionic exchange between the two materials that isn’t helped by human sweat or road salt ,the bonding agent [usually an epoxy type glue] acts as a‘buffer’ between the parts though some brands put fiber glass or Kevlar into layup as these areas as a ‘buffer’ as well so it’s incredibly hit and miss as to which brands might suffer from parts coming loose over time if at all .The issue of U.V damage is also very hit and miss as some brands use UV resistant resins in production or UV resistant clear coats ,the actual ‘damage’ is only at the surface and is in the resin binding the carbon fibers and it’s usually easy to spot as the resin will have ‘yellowed’ slightly ,it’s harder to spot with low resin percentage carbons and can be confused with clear coats peeling/yellowing or going ‘cloudy’