A core decision behind the change to Firefox Lockwise was to introduce Firefox Lockwise as a stand-alone password manager app on mobile devices. That way, it could be used to prefill login information on apps other than Firefox on mobile devices. There were also a few issues with ease of use and functionality in the original saved password system that the Firefox developers wanted to address with Firefox Lockwise. In the current versions of Firefox, the legacy login manager is no longer available. Sorry.