database insert failure because of dependencies?

[MxmUrw]

We get:

dpsa4fl-janus-tasks2_1  | Running taskprovision server
dpsa4fl-janus-tasks1_1  | Running taskprovision server
dpsa4fl-janus-tasks1_1  | creating training session with id 18328
dpsa4fl-janus-tasks2_1  | creating training session with id 18328
dpsa4fl-janus-tasks1_1  | provisioning task now with id 7nWLxhZ9Er7VCZLm1BPdJa6GRSoYZlX0ZpGe6jc7s6o
dpsa4fl-janus-tasks2_1  | provisioning task now with id 7nWLxhZ9Er7VCZLm1BPdJa6GRSoYZlX0ZpGe6jc7s6o
db1_1                   | 2022-12-08 05:39:37.253 UTC [36] ERROR:  could not serialize access due to read/write dependencies among transactions
db1_1                   | 2022-12-08 05:39:37.253 UTC [36] DETAIL:  Reason code: Canceled on identification as a pivot, during write.
db1_1                   | 2022-12-08 05:39:37.253 UTC [36] HINT:  The transaction might succeed if retried.
db1_1                   | 2022-12-08 05:39:37.253 UTC [36] STATEMENT:  INSERT INTO client_reports
db1_1                   | 	                (task_id, report_id, client_timestamp, extensions, public_share, input_shares)
db1_1                   | 	            VALUES ((SELECT id FROM tasks WHERE task_id = $1), $2, $3, $4, $5, $6)
aggregator1_1           | {"timestamp":"2022-12-08T05:39:37.254804Z","level":"ERROR","fields":{"error":"DB error: db error: ERROR: could not serialize access due to read/write dependencies among transactions\nDETAIL: Reason code: Canceled on identification as a pivot, during write.\nHINT: The transaction might succeed if retried."},"target":"janus_aggregator::datastore","filename":"aggregator/src/datastore.rs","line_number":885,"threadId":"ThreadId(8)"}
aggregator1_1           | {"timestamp":"2022-12-08T05:39:37.254850Z","level":"ERROR","fields":{"error":"DB error: db error: ERROR: could not serialize access due to read/write dependencies among transactions\nDETAIL: Reason code: Canceled on identification as a pivot, during write.\nHINT: The transaction might succeed if retried."},"target":"janus_aggregator::datastore","filename":"aggregator/src/datastore.rs","line_number":122,"threadId":"ThreadId(8)"}

[MxmUrw]

Interestingly enough, aggregation always succeeds. It might be that this error is irrelevant?