I noticed a similar effect on me in regards to critical thinking when I'm coding. My default response when faced with any coding problem now is to use an LLM.
But it gets even worse. Last year I'd get just an initial solution from an LLM and then reason about it myself. Now even that is too much work and I instead ask the same question to multiple LLMs and draw consensus from their results, skipping/easing even that second step of thinking.
Energy takes the path of least resistance. Thinking requires energy. So are our brains learning to off-load thinking/reasoning to LLMs whenever possible?