Not right now, but if I find it becoming pricy I might ask users to verify their account by phone beyond a certain usage threshold, to prevent spammers from using it.
If it keeps getting bigger I'll try other database solutions (MongoDB, DynamoDb, ...)
As this storage aims for serverless apps and it isn’t secure (anyone with access to your token can read/write to it) I assume usage won’t be too high. If that won’t be the case I’ll consider cheaper alternatives to Firebase. If it’s still stays an issue then I’ll look for sponsorship.
If it keeps getting bigger I'll try other database solutions (MongoDB, DynamoDb, ...)