The client gets an exception similar to:
ReplyError: ERR DB capacity quota exceeded
Your total database size exceeds the max data size limit, which is
10Gb for “Pay as you go” databases. When this limit is reached,
write requests may be rejected. Read and delete requests will not be affected.
You can manually delete some entries to allow further writes. Additionally you can consider setting TTL (expiration time) for your keys or enable eviction for your database.
You can upgrade your database to Pro/Enterprise for higher limits.