Mac Bluetooth keyboard sluggish - and/or repeats?

Symptoms

• Press a key – no response.
• Or a several-second time lag, before any output.
• Press a key (even briefly / lightly) and several characters are output.

When observed

• After some time (hours to days).
• Usually, when the screen is locked or asleep
• Which makes entering the password, functionally impossible.

Equipment

• MacBook Air (M1, 2020)
• Apple Magic Keyboard (on Bluetooth)
• macOS Big Sur (V11.4 (20F71))

Workaround

1. Hold Shift and Option, then click the Bluetooth icon in the menubar.
• Yes; challenging when having KB trouble. 😕
• Though at least possible, since these are keys meant to be held down.
• If even this doesn't work, hopefully you have a wired KB handy…
2. Select "Reset the Bluetooth module".
• Hmm; maybe this is possible to trigger with no KB use…
3. There is no step three 😏

Shoutout to the good folks at OSXDaily.