Linode IPv6 pool and Google Captcha, iOS AppStore

I am using a /56 IPv6 pool from Linode for my home IPv6 connectivity (tunneled from home to Linode host). When using Google search, we get a "not a robot" captcha ("Our systems have detected unusual traffic from your computer network").

Also, using these IPv6 addresses it seems not possible to access the Apple iOS AppStore ("Cannot Connect to App Store"). I cannot find any traffic that would be blocked.

Is anybody else seeing the same thing, or know of a way to fix this?