BugFix [Onboarding] FXIOS-13911 Firefox loader view being distorted when passing from portrait to landscape on iPad

[FilippoZazzeroni]

📜 Tickets

Jira ticket
Github issue

💡 Description

BugFix Firefox loader view being distorted when transitioning from portrait to landscape on iPad.
Refactor Firefox loader view with UIKit.

🎥 Demos

Simulator.Screen.Recording.-.iPad.A16.-.2025-11-05.at.14.24.53.mov

📝 Checklist

• I filled in the ticket numbers and a description of my work
• I updated the PR name to follow our PR naming guidelines
• I ensured unit tests pass and wrote tests for new code
• If working on UI, I checked and implemented accessibility (Dynamic Text and VoiceOver)
• If adding telemetry, I read the data stewardship requirements and will request a data review
• If adding or modifying strings, I read the guidelines and will request a string review from l10n
• If needed, I updated documentation and added comments to complex code

[mobiletest-ci-bot]

	Messages
📖	Project coverage: 38.48%

🥇 Perfect PR size

Smaller PRs are easier to review. Thanks for making life easy for reviewers! ✨

✅ Per-file coverage

All changed files meet the threshold of 35.0%.

Client.app: Coverage: 37.05

File	Coverage
ModernLaunchScreenViewController.swift	36.73%	⚠️
LaunchCoordinator.swift	42.66%	⚠️

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