It is 2025. This is absolutely unacceptable, especially from a multi-billion-dollar media conglomerate.
It's especially unacceptable given that they can control whether or not their client app is using IPv6 by configuring their resolver to not request AAAA records.
Streaming off their website works fine. Streaming with their Android app on a Google TV Streamer doesn't work on an IPv6-supporting internet connection.
https://help.disneyplus.com/en-GB/article/disneyplus-en-au-streaming-issues