621 - WARNING - persist_presence_changes-99641 - [TXN OPERROR] {update_presence-34728b} could not serialize access due to concurrent update

This issue has been migrated from [#16734](https://github.com/matrix-org/synapse/issues/16734).

---

### Description

The are some Warnings on Synapse 1.89

### Steps to reproduce

I have this error on the log.

### Homeserver

auto-host

### Synapse Version

1.89

### Installation Method

pip (from PyPI)

### Database

PosgreeSQL 11

### Workers

Single process

### Platform

CentOS7 VM Python installation

### Configuration

_No response_

### Relevant log output

```shell
2023-11-23 11:42:50.459 cd11-comm.on-gofast.com
2023-11-23 12:42:40,592 - synapse.storage.txn - 621 - WARNING - persist_presence_changes-99641 - [TXN OPERROR] {update_presence-34728b} could not serialize access due to concurrent update
```

### Anything else that would be useful to know?

_No response_

Start with the persist_presence_changes transaction and update_presence operation named in the log, using the reported PostgreSQL 11 and Synapse 1.89 setup as context. Reproduce or trace the concurrent-update warning and establish whether it is actionable; the issue provides no file, test, or requested behavior, so a concrete done condition is not specified.

Written by the indexing model from the issue text.