It has less market share than perl or delphi (make your own judgement). It was really hyped(rightfully so, a practical lisp for production use? fun! sign me in) then declined fast.
Like most(ly dead) languages, it still has its followers, in the case of clojure, mostly a cultish group (my impression from r/clojure and other forums).
Can you explain and support the idea that the number users using the language productively declined? The state of Clojure survey seems to have held steady at 2500 from 2015 to 2020 with 60% saying they used it for work in 2015 vs 69% saying they used it for work in 2020.
Going back to 2010 we see less than 500 respondents and only 27% using it for work. A charitable assumption is that it grew substantially between 2010 and 2015 and held steady between 2015 and 2020.
Like most(ly dead) languages, it still has its followers, in the case of clojure, mostly a cultish group (my impression from r/clojure and other forums).