How did you install freshrss, and what operating system are you using. If using docker, which docker image? There are multiple freshrss images. Do you explicitly map a docker volume or are you letting docker create an anonymous volume behind you back?

On my docker install using https://github.com/linuxserver/docker-freshrss the sqlite file is at this location inside the container at /var/www/FreshRSS/data/users/_/db.sqlite I have a bind mount mapping /var/www/FreshRSS/data to ./data . So, the sqlite file is in data/users/_/db.sqlite relative to the directory holding the docker-compose.yaml file.