Placement of Pi-holes on the network

I've been running one Pi-hole for a few months now, and it's worked quite well.

I'm planning on replacing it with redundant Pi-hole/Unbound servers. I was originally going to place them both inside the house network, pretty much side-by-side physically, nothing tricky.

However, it occurs to me that there might be a reason to place the second DNS server outside of the OpenWRT router, but inside the Starlink router (which is not set to pass-through). See the drawing above.

Is there an advantage to doing it this way, or is there no point to it, or is it totally stupid and/or dangerous?