Like @Axios , I didn't install the two fixes, since I wasn't having issues on Budgie.
I can confirm that the absence of the Network Manager applet in the system tray is fairly recent, like @elfprince .
I can even specify that just a short while ago (I don't remember when), I saw it appear briefly in my session. I closed it, then reopened it, and the applet disappeared from the system tray again.
Today, since 6:45 PM (French time), the Network Manager applet has been displaying erratically.
Sometimes it appears in the system tray when a session is opened, and (often) other times it doesn't.