Theme-color not always recognised

[DPDmancul]

Sometimes the color of the tab does not follow the theme-color meta tag.
It seems not depend on the website: on the same website sometimes the color follows the tags, sometimes follows the header background color (which I select as alternate source)
VivaldiFox 3.1
Firefox 64.0

[n4n0GH]

I feel like it never detects theme-color tags at all and always reverts to it's alternative ways of finding colors which is quite irritating.
VivaldiFox 3.1
Firefox 65.0.1

[atarixle]

greetings from the year 2021. this behaviour is still present here on Firefox 90.0.2 32 Bit on Debian 10.10 Buster; official Firefox binary downloaded from the Firefox website.

[atarixle]

debian 11 Firefox from the repo: no color from the meta-tag is used :-(

[zaguragit]

same for me