The indicator draws levels based on the overbought and oversold values of the RSI indicator.

The maximum values that are equal to or have exceeded certain limits are taken into account.
That is, for example, when the price has gone into the overbought zone, the maximum price in this zone is selected for this period of time, and as soon as the indicator value has returned to a value below the overbought value, the level is fixed and the calculation of new values begins.

The same is true for oversold values.

There is a setting so that the chart also displays such levels when the price left the overbought or oversold zone and for the first time crossed the 50% limit of the RSI indicator value.
In case of repeated passes of the central line, calculations of the passage of the middle line are not performed, the indicator switches to overbought or oversold calculations.

To display levels from 50% of the RSI value, there is a setting at which price to draw the line: either at high/low prices, or at close.

The RSI period, RSI levels and line color are configured.

Enjoy it!

The first screenshot shows only overbought and oversold levels.
On the second – the same the first intersection of 50% RSI. 

The RSI indicator is at the bottom of the chart for clarity.