It's more common than you might think. I know of at least one popular email client that stores your credentials on their servers to enable features like multi-account sync and scheduled sending.
I would expect such a feature to use end-to-end encryption for the data, so that only the user can see the credentials. It does, right? Right?
Do you mean Spark? I get why they need to do it that way but I also hate that they have to do it that way because it sucks for privacy.
I bought a hardware password manager a while back and the bulk load tool sent all your creds to a cloud service. I have not used it since, and sent the manufacturer a nasty note.
It was the Ethernom Beamu, company now defunct.