X-Real-Ip is distorted when tcp routes witjh tls passthrough is used

I have a setup as described and discussed in this topic: Traefik dispatcher infront of other traefik instances. For easy understanding I copy the same overview image here:

The problem I encounter is: all traffic arriving in environment B has the HTTP X-Real-Ip header set to the internal IP address of instance A. This makes some middle-wares, like IP whitelists, unusable in that scenario. All incoming traffic is allowed as the whitelist always sees an internal IP address from an allowed address range.

Is there anything I can do about that? Any options I can change when forwarding the TCP traffic from environment A to B to preserve the original real IP from the incoming traffic?