Oonly Chat present issues: randomly and after some hours or even days, messagges doesn't refresh automatically and Odoo accuses of losing connection and getting it back automatically (sometimes the session even expires).

On my Odoo log file I get this:

2021-07-22 14:38:04,134 88563 INFO odoo odoo.service.model: SERIALIZATION_FAILURE, retry 1/5 in 0.4027 sec...
2021-07-22 14:38:04,134 88563 ERROR odoo odoo.sql_db: bad query: UPDATE "bus_presence" SET "last_poll"='2021-07-22 14:38:04' WHERE id IN (19)
ERROR: could not serialize access due to concurrent update

This is my enviroment:

• VM witth 4 virtual processors and 16 GB of RAM
• Ubuntu 20.04
• Odoo 14 Community Edition
• NGINX as a reverse proxy

I have setted 5 workers (already tryed with 0, 1, and 2)

Is this a bug?