I saw a previous thread where somome with a Samsung s21 ultra had issues using a chrome cast because the app said it needed an update but the play store said it was on the latest version. They gave up and threw the chrome cast away.
I have the same issue but I can't throw my device away. It's a 70 inch visio. It's older but works well. My phone is fully up to date and only a few years old. Samsung note 20. The app is on version 188.8.131.52, the phone is fully supported and fully up to date. The visio is also fully up to date.
Thanks for reaching out. To confirm, are you getting that message when casting a video from your phone to the TV? Have you tried to use a different mobile phone and check if the same issue persists? Please reboot your mobile phone and check if it has a pending OS update.