If it is a bug as you say...I find it a useful "bug".
It works in my favour as a starting point to legalising any broadcast video exports that I do in house (in Premiere).
If I use Da Vinci Resolve for the task...I use Soft Clipping Controls on individual channels. This rolls off the luminance in a soft controleable curve as opposed to a hard clip.
With Levels (Premiere)...I drop them just a touch lower than 100% because the QC is very fussy about the transient luminance spikes. (especially in color channels)
This lowering...displays an apparent softening of the clipping which I tweak until there are no clip lines sitting at 100%.
The comprehensive report, that BM Ultra Scopes provides us with , proves it works and image quality on screen shows it works.
@ hewlett_zar. What do you use or suggest for broadcast legalising your work (in Premiere) and does your Broadcast QC accept it? ie. no rejections