[Bug]: LNURL-auth issue after migration (plunda.co)

[piotr-iohk]

What happened?

Same class of issue as Android #796, now reproduced on iOS.

After migrating from old Bitkit RN app (v1.1.6) to native iOS (v2.0.4), LNURL-auth to plunda.co authenticates as a different identity/account instead of the original pre-migration account.

Observed outcomes during repro:

• migration scenario results in different LNURL-auth identity on plunda.co (new account instead of existing)
• repro is currently considered 100% in repeated attempts

Expected behavior

Using the same migrated wallet should preserve LNURL-auth identity and log in to the existing plunda.co account created before migration.

Steps to Reproduce

1. Install Bitkit RN iOS v1.1.6 (mainnet simulator build) on iOS Simulator.
2. Create/import wallet and perform LNURL-auth with plunda.co (establish original account).
3. Migrate same wallet to native Bitkit iOS v2.0.4.
4. Open LNURL-auth deeplink (bitkit://LNURL1...) for plunda.co.
5. Observe login is not mapped to original account (new account identity).

Note: repro performed on simulator (not physical iPhone).

Logs / Screenshots / Recordings

2026-02-19-lnurl-auth-migration-ios-sim-logs.zip

Bitkit Version

• RN iOS: v1.1.6 (pre-migration)
• Native iOS: v2.0.4 (post-migration)

Device / OS

iOS Simulator (iPhone 17) on macOS (Darwin 24.6.0), not a physical device.

Reproducibility

Always

Additional context

• Scenario focuses on migration from RN app to native iOS app with same wallet.
• Issue is specifically visible on LNURL-auth (tag=login) flow against plunda.co.
• Android counterpart already tracked: #796.
• Suspected area to verify: migration/auth key derivation parity between RN and native iOS (identity continuity across versions).