As you are aware, a typical hotel (public Wi-Fi) portal uses a technique to "hijack" DNS queries to point to the hotel's "login" portal instead, regardless of what you entered into the web browser.
A few years back Apple decided to "simply" how these portal pages get presented on their devices. Their tactic is to perform a DNS check on connecting to any network to see if they can resolve any of their own domains. If that failed (as you would expect from the hotel's Wi-Fi), it knows that the device is being connected to a portal ... which then brings up this captive.apple.com page. This should only appear briefly before the hotel's page shows up. This typically should only be a few seconds, but it could be much longer.
Unfortunately, there is no method to disable Apple's pseudo portal page. The only means to avoid it, is not to connect to portals in the first place ... not very helpful, I know.
One thing you can check is if you use a VPN app with your iPad. If you do, be sure to disable it when connecting to the hotel's portal. Once successful, you can always re-enable it as needed.
The potential workaround would be to not attempt to connect to the hotel's Wi-Fi via Settings > Wi-Fi. Instead, at the iPad's Desktop, just open the Safari browser to any Internet site. This should bypass captive.apple.com and present you with the hotel's portal page.
