The $30 plan is like the old plan minus 5g uw. So a downgrade for $5 more.
$45 has 50gb of premium data, some limited international roaming and calling/texting from the US. Otherwise the same as the old plan.
The old legacy plan is still active for existing customers only and party pay discounts will be locked in 13th October for those on this plan only. So you can still keep that for $25 if you already have it.
The new $45 plan also lets you call to 30+ countries and text 200+ countries.
Referral discount is $20. There is also no new customer discount anymore. So if you are just swapping to get a phone, cheapest monthly service is $10 for that first month.