This. I strongly recommend not using it at this point in time.
SQlite really lends itself to having a spatial backend and would likely become a bit player in this space if it did, but it probably needs a major overall first.
To be specific, they changed the KNN backend, but the docs refer to the new unreleased backend. The old one is deprecated but unreleased, which is a strange confusing situation.
For the average HN reader spatialite is a tool which should be considered. If the KNN issues are a breaking point for someone, they are probably already in postgis territory.
SQlite really lends itself to having a spatial backend and would likely become a bit player in this space if it did, but it probably needs a major overall first.