This is not surprising. I have no idea why Elon Musk felt he had to change the name of Twitter which has been its name and branding for many many years, choosing X was also not one of the smarter moves either, I have seen so many complaining about the name change and what it was changed to.
Changing the name or even your branding is always risky, especially if it's been the same for many years so ut is not surprising it started to affect app store downloads.