Color mismatch in (NDI viewport capture) render target

I’m trying to output via NDI (which works) but I get strange color shifts.

The shift between render target texture (lower left) and NDI monitor (upper left) I would ignore for now.
But how come viewport (upper right) to render target texture looks so weird?

I habe played around with color depth and gamma settings (although the issue does not seem to be only gamma-related), but nothing seems to change anything, and I did not find any point where I could test if that was some (non-) linear gamma conversion or HDR/LDR issue …

(The camera is an NDI viewport capture component; and in the scene there is a post-process volume with exposure, bloom, lens flares, screen percentage oversampling and such.)

Please, if anyone of you had a pointer for me how to get the viewport look into the render target, that would be most kind and I will be eternally grateful. :wink:
Thank you very much in advance!