I assume this is just a minor problem in giving the parameters the correct label.
In export settings, tab video codec (Codec e.g. libx265), select bitrate mode = “constrained VBR”.
As far as I understand this mode, the compression is done with respect to the quality setting. If the result is below the bitrate, it is kept. Otherwise it is limited to the bitrate.
However, the labels do not reflect this. The settings are called “Bitrate” and “Quality”.
I suggest to label the parameters “Max. bitrate” and “Target quality” instead which makes clearer what it means. Additionally, as the encoder looks at the quality first, I suggest to list the quality settings on top of the bitrate setting (Currently, the bitrate settings stands on top of the quality setting).
It is just a minor change, but can help beginners to understand what happens.