There's actually loads of ways to solve this depending on what those apps are.
You haven't given us enough detail of what you are actually trying to do for anyone to give you concrete advice.
But the answer is probably a reverse proxy, checking the auth on the way. It's a standard solution for things like this, just ask your favourite AI for an example of how you'd do it.
That's what your teams are effectively already doing (redirecting through a single stable environment), they've just not realised they've setup one of their servers as an ad-hoc reverse-proxy.
Your teams could do with some senior engineers who know what they're doing.
There's actually loads of ways to solve this depending on what those apps are.
You haven't given us enough detail of what you are actually trying to do for anyone to give you concrete advice.
But the answer is probably a reverse proxy, checking the auth on the way. It's a standard solution for things like this, just ask your favourite AI for an example of how you'd do it.
That's what your teams are effectively already doing (redirecting through a single stable environment), they've just not realised they've setup one of their servers as an ad-hoc reverse-proxy.
Your teams could do with some senior engineers who know what they're doing.