Liquid Syntax Error: Unknown Tag ‘Schema'

Extensions
1

I’m getting the following error from Shopify’s side during shopify app preview, even though the build succeeds:
This is happening inside a Theme App Extension.
post-purchase-extension builds successfully
Error appears only for theme-app-extension during preview
Files affected are under extensions/theme-app-extension/blocks/*.liquid

Screenshot 2025-12-16 110140

Screenshot 2025-12-16 1101401568×387 27.5 KB

2

same issue was working fine till yesterday

3

There’s a bigger thread here: Liquid syntax error : Unknown tag ‘schema’ when running shopify app dev - Shopify CLI and Libraries - Shopify Developer Community Forums with the same report