Huge gamma shift VP9/H265

I have encountered this problem so many times before, and the work around always seems to be: "try a different format". Well now I cannot, because these videos I am trying to render are for direct website upload/hosting. The sort that plays in the background of a website, so they have to be webM files.

When I render them out they are significantly over contrasty. I thought that it might just be VLC player doing something weird, but uploded to the website, they remain way too contrasty.

Check it out:
https://interrobangstudios.co.nz/

DR delivers webm now? That is great to hear.

For your problem: there is this lengthy thread: viewtopic.php?f=21&t=101253
To understand what could have gone wrong it is necessary to know your input and output settings, format, etc.

Thanks Dante!
I've just gone down a serious rabbit hole there, but this is, I think, exactly the information I was looking for. Although I am struggling to apply it to my exact situation. Strange that I have never been pointed in this direction before after my previous posts over the years.

However, all the posts and articles talking about these issues relate more specifically to working with P3 Mac monitors, assuming that ColorSync is managing things in the P3 gamut. I am using a BenQ sRGB monitor. I couldn't afford a high-quality wide gamut monitor, so Vincent over at DisplayCAL recommended getting a good quality sRGB monitor (cheaper with good quality control) for working accurately within the sRGB colour space. As I am delivering exclusively for youtube, Instagram, Vimeo, there is no real reason to worry about wider gamuts.

So to further diagnose my particular issue:
I have my display calibrated and profiled to sRGB (similar enough to rec 709 for my purposes), gamma 2.2
I work with BRAW files mostly. I do not set Resolve to Davinci colour managed.
I have my workspace profile set to Rec709-A (mostly because all these articles above refer to it and because it is so similar to sRGB.
When I export, I usually render out to H.264 for Instagram clients (although this has a huge gamma shift when viewed in VLC, it looks fine on instagram)
And DNxHR for youtube upload (I never have any big gamma shift problems with this, but I loose saturation, which I bump up by 10 pre-export)
Now, trying to export a VP9 for the first time, I am encountering this gamma shift that I can't see a workaround for, so I am going to have to fix the root cause of the issue: Colour management.

Reading your suggested posts and links therein, I am inclined to go by the latest advice to set things up as I have detailed above. But because my ICC profile is sRGB as is my monitor, should my workspace profile be Rec709-A, when this is being described as a corrective measure to balance the difference in working in 709 and the P3 space that Mac OSX likes. This is where I am a bit confused.

Any ideas where to start?

I've just noticed something. I never use QT player. I use VLC. I just opened an H.264 export in QT player, and low and behold, it looks very similar to Resolve viewers. There is the slightest bit more contrast, and colours seem accurate to the eye. But otherwise, the best result I have seen on any render I've done on this machine. But why then do Chrome and VLC look so different, when I was under the impression they were ColorSync managed.

If you re-import the result into Resolve, does it look the same in the viewer and the scopes?
If so, it's simply different programs interpreting the flags differently (or ignoring them).

If you re-import the result into Resolve, does it look the same in the viewer and the scopes?
If so, it's simply different programs interpreting the flags differently (or ignoring them).

Yes, and this video looks great in QT Player as well as youtube. But the very same one rendered out as a webM file and uploaded to my website directly is way over contrasty.

See here:

vs
https://interrobangstudios.co.nz/

So the mp4 has no issues, but the .mov does.