There is a firmware bug in Mac OS 12.3 that renders the update impossible to install on any 2021 14 or 16 inch MacBook Pro that has had it’s logic board replaced.
Just to post one more URL:
Ben Kenobi: He can go about his business.
Stormtrooper: You can go about your business.
Ben Kenobi: Move along.
Stormtrooper: Move along. Move along.