[BUG] Max 5x → Max 20x upgrade blocked by phone verification loop ("already verified")

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) and this hasn't been reported yet
- [x] This is a single bug report (please file separate reports for different bugs)
- [x] I am using the latest version of Claude Code

### What's Wrong?

### Preflight Checklist
- [x] I have searched existing issues and confirmed this matches a known pattern (see related issues below)
- [x] This is a single bug report
- [x] I am attempting this on claude.ai (web), not Claude Code CLI

### Summary
I cannot upgrade my Claude Max plan from 5x to 20x. The upgrade flow prompts "Add a phone number to protect your account." When I enter my phone number (already verified on this account), the system responds: "Your account is already verified. Try refreshing the page." This creates an unresolvable loop that fully blocks the upgrade.

### Steps to Reproduce
1. Log into claude.ai on an active Max 5x plan
2. Go to Settings → Billing → Upgrade to Max 20x
3. Complete order details / payment method confirmation
4. Modal appears: "Add a phone number to protect your account"
5. Enter phone number → error: "Your account is already verified. Try refreshing the page."
6. Refreshing does not clear the modal or allow the upgrade to proceed

### Troubleshooting Already Completed (all produce the identical error)
- Tested in Firefox, Vivaldi, and Chrome
- Tested on desktop and smartphone
- Tested on both Wi-Fi and mobile data
- Cleared cache and cookies in each browser, full logout (not just refresh), restarted browser
- No VPN active, no browser extensions enabled
- Verified billing details and payment method are current
- Manually entered card details (bypassing Stripe Link) — same error
- Confirmed clock/time settings are automatic

Because the error is identical across every browser, device, and network combination, this appears to be a server-side account flag (verification status) out of sync with the upgrade flow's check against it, rather than any client-side or network issue.

### Related Issues (same failure pattern)
- #34229 — [BUG] Phone verification
- #56281 — Can't upgrade Max 5x → Max 20x: payment fails, support unresponsive
- #55266 — Max 5x → Max 20x upgrade fails, reproducible across multiple days/cards
- #62746 — Max 5x → Max 20x upgrade fails — same PaymentIntent pattern
- #59027 — Same bug family, marked resolved — requesting similar fix applied here

### Impact
This is blocking a paid upgrade ($100 → $200/month) on an active subscription. I've already opened a support ticket via Fin (in-app chat) with no resolution yet.

### Request
Could someone confirm whether this is the same backend verification-flag issue as #34229/#59027, and clear it on my account? Happy to provide account email via DM/private channel if needed.

### What Should Happen?

Entering an already-verified phone number should either skip the verification step entirely (since the account is already verified) or successfully re-verify and allow the Max 5x → 20x upgrade to complete and process payment. Instead, the modal returns "Your account is already verified. Try refreshing the page." and blocks the upgrade indefinitely with no path forward.

### Error Messages/Logs

```shell
"Your account is already verified. Try refreshing the page."

This message appears in the "Add a phone number to protect your account" modal immediately after submitting a phone number during the Max 20x upgrade checkout flow. No verification code is sent. Refreshing the page does not clear the modal or allow the upgrade to proceed.
```

### Steps to Reproduce

1. Log into claude.ai on an active Max 5x plan ($100/month)
2. Go to Settings → Billing → Upgrade to Max 20x ($200/month)
3. Review order details on the Max plan checkout screen
4. A modal appears: "Add a phone number to protect your account"
5. Enter phone number (already verified on this account) and click "Send verification code"
6. Error appears: "Your account is already verified. Try refreshing the page."
7. Refreshing the page does not clear the modal; the upgrade cannot proceed

### Claude Model

None

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

N/A — no prior working attempt to compare against.

### Claude Code Version

N/A — this issue occurs on claude.ai (web), not Claude Code CLI.

### Platform

Anthropic API

### Operating System

Ubuntu/Debian Linux

### Terminal/Shell

Other

### Additional Information

Screenshots attached showing the verification modal and the "already verified" error. This matches reports in #34229, #56281, #55266, #62746, and #59027 (marked resolved) — appears to be a recurring backend verification-flag bug tied to plan-upgrade checkout, not specific to any device, browser, or OS.

No repository files, tests, or entry points are identified; the report concerns the claude.ai web checkout rather than Claude Code CLI. Start by reviewing related issues #34229, #59027, #56281, #55266, and #62746, then confirm ownership with the existing support ticket. Done would mean the verified account can complete the Max 5x to 20x upgrade without the verification loop.

Written by the indexing model from the issue text.