[AltruisticGapHN]

If anyone's still reading this or anyone cares here is what I found out:

- the issue I was experiencing is with a lower quality encoding vp9 stream - from a video that was recently uploaded (explained below)

- though I didn't trust smaller filesize VP9 streams initially, they look in fact noticably better - the picture is smoother, cleaner, the artifacts of compression are less visible. Where AAC can have jittery/glittery distracting dots moving in the background in areas where you have subtle gradients (eg. a plain wall) - Vp9 has none of these, those areas look smoother and cleaner and it gives an overall nicer looking picture without compromising the detail as far I can tell

- Opus audio stream appears to have less of the ReplayGain issue, I'm not sure - but since I downloaded Opus instead of the 140 m4a stream I notice I dont need to adjust the volume compared to viewing same video in YouTube - and since the codec is newer anyway and the filesize is relatively the same or a tad smaller - also it is in 48k not 44k, I am going to download Opus from here on

- a very confusing thing is it appears ; for a recent upload ; you can have an initial VP9 stream of say 500mb which is in fact no better than the AAC and havs the grainy artifacts - and the vp9 stream gets replaced weeks later by one significantly smaller like 400mb vs 500 mb !! and looks way better . whic hsuggst there was a first pass with low quality encoding, replaced by a higher quality encoding later - therefore my assumption that larger filesize is better was wrong