Hi Ksheetiz Sharma,
Since you’ve already tried changing the lock-screen image, DISM/SFC, and a Windows repair reinstall, I’d avoid repeating those steps.
As this specifically occurs after a cold boot, please try:
- Disable Fast Startup in Control Panel > Power Options.
- Fully shut down and test several cold boots.
- If it persists, install the latest compatible graphics driver from your device/GPU manufacturer.
If the problem remains, report it through Feedback Hub (Win + F) with your Windows build and the steps needed to reproduce it.
Please note that this is a user-to-user support forum. Moderators, contributors including external Microsoft employees cannot directly intervene in Microsoft product features or access back-end systems. Our role is limited to providing technical guidance on reported issues, requests, or ideas.
I hope this helps narrow it down.