KV Bulk Write REST API returns 502

We are calling the “Write multiple key-value pairs” to bulk write KV pairs.
PUT: https://api.cloudflare.com/client/v4/accounts/{account_id}/storage/kv/namespaces/{namespace_id}/bulk

Since Dec 2023, this endpoint started to frequently respond with status code 502 and a HTML body.

<head><title>502 Bad Gateway</title></head>
<center><h1>502 Bad Gateway</h1></center>

For reference, this happens mostly when we are making more than 4 concurrent requests to this endpoint, and at least one of them will come back with a 502.

Has anyone come across this and what could be the reason?