It is natural selection , you release people smell your product if is good for usage some will keep it , downloads will depend on audience,
each product gets a peak level , we are not sure how much will stay in top untill new product will take its place unless it is world nr 1.
Get back to our Covid , you get more downloads when you increase mobility, "the virus" must be promoted , the users are promoters keeping one user is importat as he can spread your app that means you should get involved , do not release and leave it there , take care or users reviews and answer people ....one review can make it more visible, google algoritms depend on user active reviews .
App mobility will increase when you grow your audience, make your apps usage suited for large number of people.