In the war between Sony, Microsoft, and Nintendo on who can present the vaguest patch notes, Switch system update 9.1.0 continues the fight. However, in addition to, “General system stability improvements to enhance the user’s experience,” this patch actually contains a specific fix!
Switch update 9.1.0 resolves an issue where the color animation and “click” didn’t work correctly when attaching the Joy-Cons to the Switch. Apparently this bug was introduced with the release of system update 9.0.0 or 9.0.1 back in September.
So, if the small animation and audio glitch was getting on your nerves, today is your lucky day. Most people likely didn’t notice the bug at all, but any little bit of polish helps.