People don’t cancel things because they’re expensive, costs are a known and predictable quantity. They cancel things because they don’t make enough to justify the costs.
In this case, it actually was due to unknown and unpredictable costs. They were about to start production on S2 when the strikes hit. They delays spiked the costs of an already expensive show (S1 cost an estimated $175M) which made it less tenable for Amazon. This happened to quite a few shows during the pandemic and during the strikes – renewed because it made financial sense, then pandemic/strike spiked the cost, and then they canceled the renewal.
Thankfully, the work you have done (along with your competitors) in making headless CMS's viable not just for devs but also for content maintainers has made CMS work far more enjoyable.
It's awesome that you not only built out the dream most agency devs have, but made a successful business out of it at the same time.