Noting the low frame rates, the game may not be optimized yet.
The wild speculation is this is running on the current Switch. The game releasing Spring 2022 could be hinting a new Switch on the way. It lines up perfectly with the current Switch release. Hardware announcement in winter, release in March. You have to have a game to sell the hardware so here it is. From the latest direct, BOTW news will come at the end of the year. Another potential seller of new hardware.