NotebookLM inaccessible in supported region

I’m trying to start use NotebookLM but it always redirects me to notebooklm.google/?location=unsupported without any error messages, despite my region being supported, according to Frequently Asked Questions - NotebookLM Help and Available regions for Google AI Studio and Gemini API  |  Google AI for Developers

What are real restrictions?

Getting the same issue with NotebookLM.