Home Assistant Certificate Authority is not trusted, only in tablet

I have an annoying error " Home Assistant Certificate Authority is not trusted" whenever I (or any add-on) tries to open map, but only in my tablet. Opening map is refused. Both, my phone and browser are perfectly ok with that.

How did you install the certificate?
How old is your (Android?) tablet?

If it’s letsencrypt and an old android tablet, this is a known issue.

As far as I remember I have not. I do not use remote access.

I use Yoga Tab for HA so it is old. I used HA with that same tablet without problems about a year. Issue is from this summer, before it worked without problems. Also complaining about certificate only when using map makes no sense for me.