The series is rumored to feature an attack team with a giant mecha, and will have Kiyotaka Taguchi (Ultraman Orb, Ultraman Z) serving as main director. Ultraman Blazar has teased something for April 21st.
[Rumor info from Ultra Zero Fight]
UPDATE (3/25/2023): Now with the official teaser trailer coming from Tsuburaya's official YouTube channel. It's the same trailer as the one seen in Ultraman Decker Finale, only difference is that it is now widely made available for the public to see.