`google.com##.hdzaWe` blocks the AI summary. This is better than udm=14 because it doesn't suppress the other sometimes-useful non-AI Google answer blocks.
adding easylist - annoyances (specifically the 'ai widgets' section) to your ublock filter lists should get rid of it! it doesn't catch it 100% of the time (the AI summary escapes when there's links above it in search results), but it gets rid of it most of the time.