Lovelace UI temperamental entities after upgrading to 2021.1.15

After upgrading to 2021.1.15 once of my sensors and some switches are temporally showing as unavailable every few seconds:

Overview - Home Assistant

This sensor is an MQTT sensor, the MQTT messages are being published correctly every 60s:

Any idea what could be causing this? I’m running HA docker image on a Synology NAS. Before upgrading the system has been running nicely for many months.

I managed to fix it by updating Mosquitto and HA to the latest version. I was getting lots of MQTT disconnected issues in the logs.