removal of apple-mobile-web-app-capable results in splash screens not working

[jwanner83]

Link to the code that reproduces this issue

https://github.com/jwanner83/next-apple-web-app-issue

To Reproduce

1. Checkout this repo https://github.com/jwanner83/next-apple-web-app-issue

Working example with workaround

ScreenRecording_01-04-2025.22-37-41_1.MP4

In this example, I am adding the required meta tag in the root layout through html: https://github.com/jwanner83/next-apple-web-app-issue/blob/main/working-with-workaround/app/layout.tsx#L167

2. Go to working-with-workaround
3. pnpm i
4. pnpm dev
5. Visit the page with an iPhone and add the page to the home screen
6. Open the linked page <- You will see a yellow screen on startup of the page

Not working example

ScreenRecording_01-04-2025.22-38-47_1.MP4

In this example, I am simply using the appleWebApp property inside the Metadata object. https://github.com/jwanner83/next-apple-web-app-issue/blob/main/working-with-workaround/app/layout.tsx#L6 (This used to work before v15.0.0 / before the pull request #70363 was merged and released)

7. Go to not-working
8. pnpm i
9. pnpm dev
10. Visit the page with an iPhone and add the page to the home screen
11. Open the linked page <- You will see a black screen on startup of the page, not the desired yellow startup image.

Current vs. Expected behavior

I understand that the tag apple-mobile-web-app-capable is marked as deprecated and should be replaced with mobile-web-app-capable but for the sake of not breaking things, that safari requires, I would want the tag to be added in addition to the mobile-web-app-capable.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.2.0: Fri Dec  6 19:02:12 PST 2024; root:xnu-11215.61.5~2/RELEASE_ARM64_T6031
  Available memory (MB): 36864
  Available CPU cores: 14
Binaries:
  Node: 20.18.1
  npm: 10.8.2
  Yarn: 1.22.22
  pnpm: 9.15.2
Relevant Packages:
  next: 15.1.1-canary.25 // Latest available version is detected (15.1.1-canary.25).
  eslint-config-next: N/A
  react: 19.0.0
  react-dom: 19.0.0
  typescript: 5.3.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Metadata

Which stage(s) are affected? (Select all that apply)

next dev (local), next start (local), Vercel (Deployed)

Additional context

The pull request #70363 which fixes the issue #70272 changed from the meta tag <meta name="apple-mobile-web-app-capable" content="yes" /> to <meta name="mobile-web-app-capable" content="yes" /> because apparently chrome tells the user that apple-mobile-web-app-capable is deprecated and should be replaced with mobile-web-app-capable. It was released with v15.0.0-canary.175 / v15.0.0

Unfortunately, the extremely bad documented apple splash screen feature for pwa https://developer.apple.com/library/archive/documentation/AppleApplications/Reference/SafariWebContent/ConfiguringWebApplications/ConfiguringWebApplications.html doesn't work when the <meta name="apple-mobile-web-app-capable" content="yes" /> isn't set.

The problem only occurres on iPhone devices.