In the attached 1-day trend, the last 2 hours or so is when people went into the PSL room for the PSL maintenance.

The control signal glitched only once during this time (bottom left), but the out-of-loop signals (right column) were glitching for the entire period.

Apparently the fan/AC/makeup air in the PSL room cause glitches downstream of the RF AM stabilization, and the RF AM stabilization doesn't see the effect. This is very different from the glitches that we've been suffering from, where the effect was most visible in the control signal.

One of the suspicions was that something is mechanically loose and couples to vibration/acoustic, causing the glitches in the observation mode, but it doesn't seem to hold true inside the PSL room.