From an article in late February...
The Frozen Four will be played at PPG Paints Arena in Pittsburgh, the home rink of the NHL’s Penguins, on April 8 and 10. The venue, which last hosted the Frozen Four in 2013, will be limited to around 5,000 tickets per the NCAA’s guidelines.
https://www.inforum.com/sports/hockey/6899766-NCAA-hockey-chair-regional-and-Frozen-Four-attendance-capped-at-25-of-building-capacity