Common for these degas bottles to already have developed fractures in the form of hairline cracks that when at just the right temperature will either allow air in or coolant out.
Once the system loses it's pressure via cracks (any in the plastic plumbing) it's known to start with losing of interior cabin heat, overheating or simply pissing coolant directly behind the drivers front wheel.
Very hard to see those cracks as they all form on the back side of the bottle up against the firewall, near impossible to see from the front side. Never tends to crack in the front of the bottle, always along the backside firewall. Cracks will hold pressure for a while but eventually she can hold no more.
Re&Re - OEM Degas Bottle - GEN 1 V8
I drove with mine for a good month, topping up the level in the degas bottle twice over, while at the same time, the no heat at idle and uneven heat from either vents issues. Could not spot/find a leak anywhere, then suddenly one day noticed it was starting to drip coolant directly onto the ground behind the drivers front wheel.
NEVER did overheat once but on the last night drove home without any cabin heat. Air in system, defective Aux coolant flow pump and DCCV.
At that point I had already managed to gather all the parts involved with the exception of the degas bottle. Had to rush around and do some switching on the bottle. The Tasca ordered bottle eventually made it, returned "it" to the local dealership for full expensive Canadian refund, no restocking fees, Ha!
PS: just to prove my OCD, I cleaned that cracked degas bottle, inside out before taking pictures of it, sick huh!