What you’ve been receiving is a “Preliminary Notice” of a General Meeting, and whilst I always issue those as is provides Owners with both a reminder that a General Meeting is on the horizon and an “invitation” for additional Agenda items to be submitted, it’s not a requirement of the Strata Schemes Management Act in NSW – and mores the pity!
On the basis of your other post concerning a Motion to elect an Executive Committee, it appears that your current Strata Manager (SM) is doing things strictly by the book, so your solution is to (at least) elect a Committee, to elect the Office Bearers, to formally vote to require your SM to provide “Preliminary Notices” in advance of all future General Meetings, and for the newly elected Secretary to provide a written instruction in that regard to the SM just before your O/C delegates that and other functions to them in their Agency Agreement.