Steps to reproduce:
Haven't figured out a way to reliably reproduce, but has happened like four times in the last hour. I've seen it happen on command+n (new window), command+shift+n (new private window), and command+shift+t (re-open last closed window).
A new window opens.
Orion, OS version; hardware type:
Orion 0.99.112.1-rc (WebKit 613.1.12)
macOS 12.2.1 (21D62)
MacBook Pro (15-inch, 2018)