The "fixes" package, formally known as a reconciliation bill, was written under special budget rules, known as reconciliation. Under this procedure, the "fixes" bill cannot be filibustered and only needs a simple majority to clear the Senate. That is why Democrats resorted to the parliamentary maneuver after they no longer have the filibuster-proof 60 votes in the Senate.
The "fixes" bill would add more than 60 billion dollars in cost to the overall legislation that has already become the law of the land. It will expand insurance subsidies for middle-and lower-income families, while scaling back the bill's taxes on expensive insurance plans.