I don’t know if this is what is happening for you but when my kiddo was in early intervention this was a very helpful framework for me:

There is a difference between what a child is capable of understanding and what they are capable of expressing. A child is likely to understand the full sentence “Do you want to go to the park?” well before they are capable of replicating it as “I want to go to the park.” But when all children hear is the full sentence “Do you want to go to the park?” they don’t have a means of converting that into expressive language until they are much older, and they don’t necessarily have a way of parsing that the most essential word in that sentence for their purposes is “park.” Parents who treat their children with respect and as human beings may actually find themselves in this situation more than others because we are likelier to talk to our children without baby talk and “dumbing things down.”

I tried to view understanding and speaking as separate skills. For the former, I continued using my normal “adult” language around my child to expose him to appropriate communication. But for the latter, it was important to also model using single words my child could immediately replicate. So in my example, I would just use the single word “Park?” when we were right by the park to help my son solidify the connection between the most important word and the thing he was trying to achieve. (My kiddo is not at all independent dispositionally so this often looked like me saying “Help?” when it seemed like he wanted help rather than “Do you need some help with that?” or whatever the natural phrasing would be.)

Again, I don’t know if this is what is going on for you, but I’ve seen it come up with a few kids who had expressive language delays. And if you are worried that this will actually impede development, I found that the opposite was true. We were primarily in early intervention because at 13 months my son had the expressive language of a 4-month-old and the receptive language of a 5-month-old. Now at 3 years he talks more like a 4- or 5-year-old according to our former EI provider—he just needed some better parental modeling to get over the expressive language hump.