"This application requires iOS 14.0 or later" pop up

If you are experiencing any difficulty with third-party apps then please contact the app developer directly --> How to contact an app developer - Apple Support

Ask the App developer to release the app for lower iOS versions also. Netflix has done it.

asdyvv Said:

"I hope to solve this problem"

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Thank you for the screenshot.

For reference...

Updating an iPhone:

What to Update: Installed apps and the iOS.

How to do so...

A. Verify Compatibility:

Identify your iPhone model. The first thing that comes to mind in incompatibility being the culprit. So, confirm the model of your iPhone. If iPhone model is incompatible with iOS15 then it is because you iPhone does not meet the hardware requirements for this iOS version(s).

B. If Compatible...

1. Back Up First:

IMPORTANT: If you have an option to update, however, then be certain you backup your iPhone first. That way, you will have something to restore your iPhone from should anything go wrong with the update

then...

2. Proceed with the Update:

Use my User Tip:  Update your iPhone Using a Computer - User Tip