We've now gone from having an entirely unique jumper, as every other team in the competition does (to differing extents), to having one which is basically indistinguishable from the side/back with another team.
TBH I considered you as just having a bit of a ramble when I first opened the thread, but the further I read, the more I found myself agreeing with you.
And the shots you've provided demonstrate your point well. Previously you wouldn't question, even at a glance, whether it was a Carlton guernsey in those pictures, yet you had me looking twice at those examples.
While it may seem petty, guarding the brand has seen companies wiped out of existence and millions of dollars pass hands and in an era where brand protection is regarded so vitally, it's surprising this one slipped through.
So what can we do about it now? One suggestion I have, more suitable with Port's black jumper, is to have teal coloured player numbers on the back of the jumpers. It really wouldn't mess with Port's design and would make the designs far easier to distinguish. So if it bothers you so much, I encourage you to pursue this, or more viable solutions, with the club.