From what I know, Gnome is not able to define battery charge thresholds
(power-profiles-daemon is what manages this in Gnome, Bastien Nocera / power-profiles-daemon · GitLab, it will soon be replaced)
On my systems (thinkpads T and X series), I use tlp to define battery thresholds, and that is working perfectly fine.
Install: dnf remove power-profiles-daemon followed by sudo dnf install tlp
Start by default: systemctl enable tlp.service
You find more information here: Fedora — TLP 1.6 documentation