SPFX fails to load webparts after logging in to site

[vystartasv]

Target SharePoint environment

SharePoint Online

What SharePoint development model, framework, SDK or API is this about?

💥 SharePoint Framework

Developer environment

Windows

What browser(s) / client(s) have you tested

• [ ] 💥 Internet Explorer
• [x] 💥 Microsoft Edge
• [x] 💥 Google Chrome
• [ ] 💥 FireFox
• [ ] 💥 Safari
• [ ] mobile (iOS/iPadOS)
• [ ] mobile (Android)
• [ ] not applicable
• [ ] other (enter in the "Additional environment details" area below)

Additional environment details

• browser version chrome -Version 139.0.7258.128 (Official Build) (64-bit), edge - Version 139.0.3405.119 (Official build) (64-bit)
• SPFx version 1.21.1
• Node.js version v22.16.0
• etc

Describe the bug / error

After logging in to SPO site it doesnt load custom webparts. Placeholders are left in place. On refresh it works fine. This is affecting multiple production deployments and spfx versions

Steps to reproduce

1. emty cache
2. log in to spo

Expected behavior

webpart to be loaded