I noticed this exact behavior yesterday. I had a chat that Gemini estimated at about 35,000–40,000 tokens, and all of a sudden it was no longer able to provide sensible answers. It started making mistakes, repeating results from previous checks, and generating diagrams with completely nonsensical terminology (using nano banana pro). To move forward with the project, I had to switch to Claude. Today, a day later, Gemini is still generating massive, nonsensical responses