One concern I see on a regular basis is the lack of regulation with chimney installations, including new construction.
For reference here is the warning label clearly print on the flue system for the installers to follow:
As you can see pretty simple to follow but rarely adhered to.
As you can see this is just one example of violations to clearances to combustibles I find regularly. Cardboard insulation baffles leaning against the flue system, a fresh air vent against the flue liner, and a natural gas line that has been run past the flue system 🤦♂️.
Any system new or old, I highly recommend having your fireplace inspected by a CSIA certified professional before use!