To clarify, all my reported behavior is with the GNU NS-variant of Emacs. macOS voice dictation worked for me in 29.4. It does not in 30.1.
I have not used the Yamamoto fork in over a year and it is not installed on my system.
All builds that I have been using have come from MacPorts package emacs-app. https://ports.macports.org/port/emacs-app/details/
Were you on Intel or ARM and which macOS version worked for Emacs 29.4? I have Intel macOS 12.7.6 and dictation does not work with Emacs 29.4 for me (or 30.1 or current master). It could be a configuration issue or something else.