Failed to fetch X user after social login - sudden breakage

[EmergeGroup-ThoNguyen]

• SDK version: thirdweb@5.114.1 - Exact error from browser console:
  Error signing in with x Error: Failed to fetch X user after login.

• Framework: React / Next.js 15.4.5 (App Router)
• Note: Working fine until recently with no code changes on our end. The X OAuth flow completes (OAuth popup closes) but Thirdweb fails to resolve the user profile afterward.

[linear]

BLD-556