iOS 13.1.1 si iOS 12.4.1 were blocked for installation on iPhone, iPad, and iPod Touch by Apple last night. The procedure is quite normal for the Apple company, and this is because the Americans are used to blocking the installation of older versions shortly after release.
iOS 13.1.1 was released the same week as iOS 13.1, but iOS 13.1.2 was released shortly after to fix other issues. iOS 12.4.1 was released a long time ago by Apple, but iOS 12.4.2 was released to solve some problems of phones that cannot install iOS 13.
iOS 13.1.1 and iOS 12.4.1 have higher versions available for installation for everyone at the moment, so there is no reason to offer them anymore. Apple still left them active during installation for quite some time after replacement versions began to be distributed to iDevice users.
That said, iOS 13.1.1 and iOS 12.4.1 are completely gone, with Apple forcing everyone to install only iOS 13.1.2 and iOS 12.4.1 starting today.
