LLMs can speed up top-down thinkers, especially those who didn't later drill down to understand the details. Bottom-up thinkers are hindered because the LLM use takes away the info that actually helped them understand and solve problems. This is one source of the discrepancy of positive opinions and perceived productivity boost between some devs and especially between managerial types and devs.

Was this a developer who has been forced or pressured to use LLMs?

I know that should that time come for me, I'm not going to burn myself out wrestling to make something good.