Missing sensor card history data

I’m not sure since when this happens but all of my sensor cards stop showing history data after a couple of days running HA.
I run HA in a Docker container on a Synology NAS.
HA version: 2021.8.6
DB file is almost 3Gb big not sure if this is normal.
Does anybody have an idea?

How many entities do you have, and what value does purge_keep_days of recorder have ?

Take a look here :

Thank you francisp for your quick reply.
I have 541 entities and in my configuration.yaml is no purge_keep_days parameter defined.
I will take a look at the link that you provided.

if you don’t have purge_keep_days, then HA keeps 10 days.

purge_keep_days integer (Optional, default: 10)

Specify the number of history days to keep in recorder database after a purge.

Still, 3Gb is a lot of data.