"notify" in passive voice
Solution 1:
First, (2-1) is simply wrong. There is no way that that can be parsed as grammatical. So I'm going to discount that and simply have examples (1) and (2), which you've numbered (2-2).
Your other examples might be better expressed as
- You will be notified of subsequent updates
- Subsequent updates will be notified to you.
Both are licensed:
Inform (someone) of something, typically in a formal or official manner.
‘you will be notified of our decision as soon as possible’Give notice of or report (something) formally or officially.
‘births and deaths are required by law to be notified to the Registrar’— Oxford via Lexico
The active forms of your examples are
- [We] will notify you of subsequent updates
- [We] will notify subsequent updates to you.
Thus the object of notify (the patient in passive forms) can be either the recipient or the notification itself.