From Wikipedia:
https://en.wikipedia.org/wiki/NBCSN
On January 22, 2021, after its rights to the NHL were transferred to ESPN and TNT, NBCUniversal announced that the network would shut down by the end of the year. NBCSN closed on December 31, 2021, with its sports properties moved to Peacock, USA Network, and other NBCUniversal networks.[3]
On October 2, 2025, as part of a new carriage agreement with YouTube TV, NBCUniversal announced that it would launch a second incarnation of NBCSN, with its launch date later confirmed for November 17, 2025. The new iteration of the channel is designed to be a linear television outlet for NBC Sports after the upcoming spin-off of NBCUniversal's other cable networks (including USA Network) as Versant, primarily carrying content that was previously exclusive to Peacock (although certain sports properties will remain exclusive to the streaming platform).
@alizadavida NESN (New England Sports Network) carries Celtics games.