GLM’s monitor icon shows a "Clip" or "Prot" panel. What does this mean?

The ‘Clip’ panel indicates that the monitor’s audio is clipping. To solve this, reduce the input signal level or the output level.

The ‘Prot.’ panel indicates that the monitor is in its ‘Protection State’, which limits and potentially changes the output. To solve this, you need to reduce the level and wait until any monitor overload clears.