Wearing diapers won't cause loss of bladder control itself but if you do wear the diapers all the time and decide to just pee in the diaper without holding the pee back then eventually after around a year or so then your bladder muscles may become a bit weak.
I started wearing diapers all the time and suing them instead of the toilet and I started just peeing in the diaper whenever I felt I needed to pee and since I stopped holding my pee in and just peeing in the diaper my bladder muscles have gotten a bit weak.
Now if I don't wear diapers I'll wet my pants but I love wearing diapers and would not go back to using the toilet anymore nor do I want to wear regular underwear anymore.
So you can lose some bladder control if you start wearing and using the diapers all the time instead of using the toilet.