Seen on marmot. Would possibly make sense to use a more distinctive color scheme, in particular now that the gates get installed with extensions.

Was this before or after my fix?

Surprisingly, after too. I'm doing some work in this area to complete #1390, will probably see there what the problem if there is one or if it's just a setup issue on my end.

In PipeRendererTESR.pipeGateRender, I replaced:
if (pipe.pipe.gate.isGateActive())
by
if (pipe.renderState.isGateLit())

That did the trick. It makes sense with the limited understanding I'm re-acquiring - let me know if I got it wrong. Otherwise, I'll check that in.

Pushed a fix based on the following analysis. There's still some more work on the texture though. Making the dark gate grey instead of dark red will probably help seeing the different, but even so, the redstone fader gets hidden when the gate is active. Is that intended? If not, we can move to a different color scheme, e.g. red=off, green=on

Oh, yes that should do it.

Meh, not a big deal about the fader.