Hello,
Our VS code extension received an update yesterday which made nRF Debug the default plug-in for debugging (replaced the third party cortex-debug). Can you please give this a try and see if you get the same error?
Also, what SDK/toolchain is your current project based on? Reason I'm asking is that our latest SDK (v2.1.0 at time of writing) includes GDB version 9.2 if you install it via the toolchain manager.
Another alternative is to use Ozone for debugging: https://nrfconnect.github.io/vscode-nrf-connect/connect/debug_app.html#debugging-options
Best regards,
Vidar