Loundness History Graph, what is exactly displayed?

At the moment I am learning everything to get the right loudness level for YouTube. So far what „Integrated“, „Short Term“ and „Momentary“ do and where the first one should fall is clear to me.

What I am not sure about are the line and bar colors in the Graph (except the one of „Integrated, which is obvious).
In which case does the line for „Short Term“ turn red? Also the bars on the top, what does it mean, when the lower one has red segments. What kind of limits are reached with that?
There seems to be no explanation for this in the Resolve-Manuals.

In which case does the line for „Short Term“ turn red?

The Loudness data curve will reflect a red curve when the signal is above target whereas a blue curve indicates signal that is below target or within tolerance.

For short form content (e.g. advertising or promos), the Maximum Short Term Loudness is -18LUFS or +5LU relative when adhering to EBU R128.

The Short Term curve in the Loudness Track will turn red at +3LU relative, matching the behaviour of the Short Term and Short Term Max readings within the Meters panel's Loudness Metering.

Also the bars on the top

The green bar at the top of the Loudness Track indicates the presence of Loudness data.

Light green indicates the data currently written, whereas dark green indicates previously written data.

When sections of programme are measured, this bar indicates these blocks of loudness data.

Thank you a lot, this makes it quite clear.

So there is only one question left.
Below the green bar, there are red segments, which I can avoid by reducing the fader a little.
Are those triggered by an additional target? First I thought, this happens when True Peak is hit at 0, but I always avoid this anyway.

Below the green bar, there are red segments, which I can avoid by reducing the fader a little.
Are those triggered by an additional target?

The Loudness Track provides three curves - Integrated, Momentary, and Short Term - each with a different target.

The Integrated curve displays a red curve when signals are +0.2LU above target with an EBU R128 Preference.

The Momentary Loudness curve displays a purple curve when signals are +8LU relative (–15 LUFS absolute).

The Short Term curve displays a red curve when signals are +3LU relative.

Below the green Loudness data bar red indicators reflect sample peak values above -0.2dBFS. This data is only displayed when the Integrated curve is enabled.