One could do this on Android as well. i.e. That is not unique to the Librem 5.
The article in question is fluff and is clickbait scare-news IMO. I do a lot of hiking and backcountry skiing. The ambient temps when backcountry skiing are often in the -20C neighborhood and we are out all day. The battery certainly drains more rapidly, but everyone knows to keep the phone in an interior chest pocket. When winter camping one always keeps power banks and water bottles in their sleeping bags.
It is also “known” that if you accidentally let your phone or power bank freeze, it is important to slowly warm it (e.g. in a pocket) without charging/discharging. i.e. charging and/or discharging a frozen Lion battery is problematic.