X_PWA_PUSH_SUBSCRIPTION_INVALID
Means
the push subscription is not one a browser produced
Typical cause
endpoint is not https: to a public host (localhost and an IP literal that is loopback, private, link-local or otherwise not public are refused: the endpoint is where a caller points this server), p256dh is not a 65-byte uncompressed P-256 point, or auth is not 16 bytes. Refused by pushSubscribe() before storing; a stored one is deleted by the sender
Fix
import { subscribeToPush } from '@ultimat3/pwa/client' — it sends PushSubscription.toJSON() unchanged