I think it’s $200 mil a season and in an interview they said that they planned 5 seasons, so thats where the reported billion comes from. It’s a bit misleading, but still a lot of money. RoP is certainly not as good looking, but if you’re accounting for inflation and runtime the numbers make more sense.

It’s only $715,000,000.00 for the rights and the first season.

https://www.distractify.com/p/rings-of-power-budget-per-episode

It’s not a billion, but it’s twice as much as the 3 LotR movies.