Norse is technically not old Norwegian Air. It's confusing, and airline investors based on Norway have a lot to answer for:
Norwegian Air is the "old" budget airline that almost went bankrupt during the pandemic. They had to sell a number of their slots and planes to survive. But they survived. The shareholders got wiped out.
Norse Atlantic is a new airline that was established during the pandemic with the aim to take advantage of the then cheap leasing deals for new planes - and the misfortune of Norwegian Air. They bought up a number of the slots that were previously used by Norwegian Air. They have lost a lot of money, but have survived.
Flyr is the 3rd such Norway/Oslo-connected airline. Flyr was established to do the same as Norse (try and take over traffic from the struggling Norwegian Air) although for Norway to European destinations. But Norwegian Air bounced back from possible bankrupcy, with the result being that Flyr went bankrupt a few weeks ago.
It's safe to say that Norway/Oslo-based investors have had enough of starting new airlines for the foreseeable future.