Expected result is that the Target Gamma slider would apply that calculation to what's being written to it.
RT_PostProcess is a RTF RGBA8_SRGB render target being written to by a SceneCapture Actor writing Final Color LDR, with a post process material that's overriding scene color (it's just outputting full red and and full green). It appears as though those values aren't being gamma'd, but the PostProcessInput0 values are.
Download the attached project and open it in vanilla 4.25.1
Open RT_NoPostProcess and change the TargetGamma slider, observe expected changes
Open RT_PostProcess and change the TargetGamma slider, observe nothing change
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-93973 in the post.