The majority of engineers, in my hiring experience, failed very simple tests pre-AI. In a world where anyone can code, they're no better than previously non-technical people. The CS degree is no longer protection.
The gap between average and the best engineers now, though, is even higher. The best engineers can visualize the whole architecture in their head, and describe exactly what they want to an AI - their productivity is multiplied, and they rarely get slowed down.
While this could be done by junior or senior, I think junior usually has the slight advantage in being more AI-native and knowing how to effectively prompt and work with AI, though not always.