The Pokémon HOME app has announced that there will be compatibility changes for the mobile device version of Pokémon HOME for the planned June 2021 update. Support for older versions of Android and iOS will no longer be supported.

Pokémon HOME - June 2021 Update Notification

Thank you very much for your continued support of Pokémon HOME. This notice is to inform you that the planned June update will end support for Pokémon HOME on the following mobile operating systems and devices.

Android 5
iOS 9
iOS 10
iOS 11
iPhone 5s
iPhone 6

Note: To check what OSes are compatible with your device, please consult sources such as the device manufacturer's official website. Following the update, there may be other devices on which Pokémon HOME may function imperfectly or stop working entirely. It may take time for Pokémon HOME to become compatible with newly released OSes.

Customers considering changing devices should link Pokémon HOME to a Nintendo Account in order to carry over their information. You can see whether you have already linked to a Nintendo Account by opening the Options menu and checking the Account tab.

We hope you continue to enjoy Pokémon HOME!

Pokémon HOME - Version 1.4.0 - June 17th, 2021

The details of the Pokémon HOME - Version 1.4.0 update for smartphones have been announced.

What's New

- Pokédex features have been expanded, allowing you to view Pokémon's appearances from various angles.
Note: This feature does not apply to certain forms of Pokémon.
- The Catch Calendar feature has been added to the main menu, allowing you to view your Pokémon in order of the dates on which they were caught.
- New icons for user profiles have been added.
- Announcement display has been improved.
- Other issues have also been addressed in order to ensure a user-friendly experience.

Source: https://www.pokemon.co.jp/info/2021/06/210618_at01.html