I have the exact same feeling. For me the last big leap in models was when the Codex-Family came out (GPT-5.1-Codex to GPT-5.3-Codex) and then the GPT-5.4/GPT-5

I have the exact same feeling. For me the last big leap in models was when the Codex-Family came out (GPT-5.1-Codex to GPT-5.3-Codex) and then the GPT-5.4/GPT-5.5 that brought the "Codex" capabilities back to the main stream. The GPT-5.6 family feels very different, might be a little bit more intelligent but behaving very differently, and GPT-6-Astra is along those lines. That's why my main driver still is GPT-5.5.