It doesn't indicate either of those things. It's a great tool when you're working on complex code that just reaches the limit of your working memory/attention, and has often suggested good and clean improvements for me. You may dislike it but there are people it helps.
I would hate to work at a place where advanced-but-untrustworthy autocomplete would, at all, impact the productivity of a senior engineer.
Not only does this indicate that your senior engineers' productivity is measured poorly (lines of code), but also that your senior engineers are paid to type, rather than to think.