What browser are you using? And is it installed as a normal system package (not snap, flatpak, or appImage)?
Try adding a udev rule. docs.qmk.fm/#/faq_build?id=linux-udev-rules
~Edit~ And if anyone else needs to apply this, please post your distro.
Summary
Linux udev Rules
On Linux, you’ll need proper privileges to communicate with the bootloader device. You can either use sudo when flashing firmware (not recommended), or place this file into /etc/udev/rules.d/.
Once added, run the following:
sudo udevadm control --reload-rules
sudo udevadm trigger
It helped someone else on Fedora 39 KDE who was also failing to connect. If it fixes that for you, let us know. Might turn out to be something all Fedora 39 users need. Or maybe it’s just Fedora KDE.