[Follow up to #37347] Linking an active VPN subscription from iOS to Web is not working

[hffvld]

Description

Follow-up to #37347.

Steps to reproduce

1. Launch Brave on iOS
2. Purchase VPN subscription
3. Hamburger menu > Settings > Brave Firewall + VPN
4. Link purchase to your Brave account
5. Enter email, in my case vbravetest04@gmail.com > Go to email and tap the confirmation button
6. On account.brave.com tap Link my subscription now > Observe an error

Actual result

Linking an active VPN subscription from iOS to Web is not working, and error message is shown.

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1	2	3	4	5

2024-09-04_12-32-59.mp4

Expected result

Linking an active VPN subscription from iOS to Web must work as expected.

Reproduces how often

Easily reproduced

Brave version

Brave build: 1.69 (162)
BraveCore: 1.69.162 (128.0.6613.120)

Device/iOS version

iPhone 14 / iOS 17.6.1

Affected browser versions

• latest AppStore
• latest TestFlight
• previous TestFlight

Reproducibility

• with Brave Shields disabled
• in the latest version of mobile Safari

Miscellaneous information

cc @Brandon-T @pavelbrm

[hffvld]

The same issue was observed when linking Leo's subscription from iOS to the Web.

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2024-09-04_13-43-34.1.mp4

2024-09-04_14-15-35.mp4

[pavelbrm]

Replied in Slack. Repeating here just in case.

@hffvld Deferring this to @Brandon-T for now.

As you can see on the recording, the website throws an error saying it could not find the receipt. The backend does not even get a chance to participate here.
We've seen a number of complains from users over the course of the last few months about similar behaviour, but I have not heard of any investigations/changes made client-side to mitigate it (it might be that I am simply not aware of them).

[Brandon-T]

This was fixed by: brave/brave-core#25443