@Juluca10 você já olhou esse documento?
https://documentation.meraki.com/Wireless/Operate_and_Maintain/User_Guides/MR_Splash_Page/Google_Sig...
Due to the OAuth policy changes from Google in 2023 , some devices may also not redirect to the splash page automatically. The user will receive an Error 400/403 notification in their embedded browser. For this reason, we have added a pre-splash info page for users of splash that have Google Auth enabled. This new pre-splash info page is only active on SSIDs where Google auth is configured for splash.
Google's requirement is to now open a full browser to authenticate -and not the webview/websheet/embedded browser that most operating systems launch when presented with a captive portal.
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
Please, if this post was useful, leave your kudos and mark it as solved.