/loki/api/v1/push (500) "context canceled" from distributors

I am sending logs from AWS Lambda(python) to Loki endpoint /loki/api/v1/push directly(via NLB).
It seems most of the logs are being sent to Loki successfully.
But I got the warning logs below from distributors.

"level=warn ts=2023-01-05T11:50:24.072282964Z caller=logging.go:86 traceID=2a11931ed1f9897a orgID=fake msg="POST /loki/api/v1/push (500) 2.01997ms Response: \"context canceled\\n\" ws: false; Accept-Encoding: identity; Connection: close; Content-Length: 1045; Content-Type: application/json; User-Agent: python-urllib3/1.26.9; ā€œ\nā€

Does it mean I am missing some logs?
I appreciate any help or hint.