Yes, unfortunately, the hotend cools off almost instantly for everything now, including pauses for filament changes
I removed that sensor a long time ago after it derailed the filament one too many times and killed another print. Just jumpered the connector. I do the same with weight or measurement on really long prints.
To be honest, on those long overnight prints I don't sleep well anyway and usually end up getting up every few hours to check on them anyway. I am not really sure why though, with the bowden setup, especially the long tube style on the FLUX once the filament runs out, there really isn't a good, easy, reliable way to reload it quickly. It can be done, but success ratio isn't great unless you decouple the PTFE connector from the hotend to remove what is in the tube and do a full reload, but you can't use the Load function in the middle of a print. And the nozzle is cold, so no matter what, it may 'airstrude' for a few seconds.