Flatpak runtime reached eol message

[szszszsz]

Flatpak runtime reached eol message.
Report copied from:

• https://support.nitrokey.com/t/linux-nitrokey-app-flatpak-runtime-reached-eol-message/4287

Environment:

• Application version: v1.4.x
• Operating system: Linux
• Issue occurrence: always

Expected behavior

No warnings during the update

Current behavior

When updating my flatpaks I always get this message

Info: org.kde.Platform//5.15 is end-of-life, with reason:
  We strongly recommend moving to the latest stable version of the Platform and SDK

Applications using this runtime:
  com.nitrokey.nitrokey-app

tried to find a related issue here but didn't find one.