This is getting interesting. Since I was running a bunch of tests anyway, I tried having 5 different devices with differet OS and FW. 3x IGEL OS11 (Linux/Ubuntu based), one with Horizon client 2206, 2212 and 2303. The 2206 is the only one doing it. Also tried with all 3 devices running the same FW with the same client, all with factory reset and reinstallation of the FW. Same result. 
I then tried with the windows client, just on 2206 and 2303. None of them did it. 

Sadly that "feature" is something we've been using quite a bit on our current machines, which is why we are bit sad it wasn't an actual feature after testing an update before going through and replacing 2000 devices. Maybe something to bring up as suggestion, to either allow that pause, or maybe just allow the page/broker to automatically register a smartcard (chip/contactless) or even biometrical input and just having the AD login as a backup. 

I do appreciate the suggestion. It is something we have been considering due to this, but we need the manual AD login, as we have about 50-60 external contractors and consultants (out of 12000 employees) that needs access aswell, but can't get a card issued (government healthcare). 

Any ideas or comments are more than welcome. I'll keep this updated with whatever we do for a solution.