You are performing a high number of authentications in a short amount of time.

Batch tokens are a type of tokens that are not persisted in Vault’s storage backend, but are encrypted blobs that carry enough information to perform Vault actions. Batch tokens are extremely lightweight and scalable, and can improve the throughput for token generation. Batch tokens are suitable for high-volume and ephemeral workloads, such as containers or serverless functions, that require short-lived and non-renewable tokens. Batch tokens can be created by using the -type=batch flag in the vault token create command, or by configuring the token_type parameter in the auth method’s role or mount options. Batch tokens have some limitations compared to service tokens, such as the lack of renewal, revocation, listing, accessor, and cubbyhole features. Therefore, batch tokens should be used with caution and only when the trade-offs are acceptable. References: https://developer.hashicorp.com/vault/tutorials/tokens/batch-tokens 1, https://developer.hashicorp.com/vault/docs/commands/token/create 2, https://developer.hashicorp.com/vault/docs/concepts/tokens#token-types 3