If you’re using the pull out tray kind, can remove and wash (very mafan). However I have tenants, myself and baby so we all used 7 different detergents (I rotate 3 for myself based on mood) which probably still has leftovers in the tray (No storing of detergent in the cap compartment, only pour what you need in the open compartment).
As long as your baby’s skin no issues, then no need to worry. My baby is 19mo, no issues as well. If you’re worried, can switch your own detergent to baby’s detergent or use capsules for yours then liquid for baby. 😊