I think they're referring to the Early Access Program, which was a one-time pre-launch Dutch auction in advance of general availability. Note that that is orthogonal to a domain being premium or not. During the last day of EAP, you might have seen the price of a non-premium domain be something like $130+12/yr. Whereas for a ~$70/yr premium domain, it'd have been something like $130+70/yr.
Regardless, forum.dev was registered in 2021 (you can confirm via WHOIS), which was long after the Early Access Program for .dev ended in 2019.
Regardless, forum.dev was registered in 2021 (you can confirm via WHOIS), which was long after the Early Access Program for .dev ended in 2019.