[UPDATE] Nintendo Switch firmware update version 12.0.3 available, only to be pulled after issues
Ver. 12.0.3 (Released June 7, 2021)
General system stability improvements to enhance the user's experience.
Source
UPDATE: SciresM has commented on the matter. It appears Atmosphere users will need an update, which will happen soon, likely sometime tomorrow.
Looks like atmosphere will need a (probably minor) update; I'm indisposed for the next ~12 hours, but unless something crazy happens I'll try to get stuff sorted by tomorrow. https://t.co/QqyeRLy1yt
— Michael (@SciresM) June 8, 2021