I found a recentish (2021) survey at [1] which suggests that in 2021 ML was some way behind web development, sysadmin stuff, and data analysis among Python users (and didn't seem to be on the way up the list).
The obvious next question being, what's the difference between ML and data analysis from the perspective of the survey participants (is ML a strict subset)? Given the values don't add up to 100%, there's likely lots of overlap and so you could easily have web developers choosing Python for the ML ecosystem.