tty devices are created with GROUP="dialout" in 242, by the rules from /lib/udev/rules.d/50-udev-default.rules. The specific line is:
This is a change since e.g. 239, where GROUP="uucp".
This change breaks at least the current version GPSD, which expect any GPS devices to be in the "uucp" group.
It could be that the change is intended. In that case, this is rather a sci-geosciences/gpsd-3.17-r2 bug.
Indeed, the change is intentional. I don't want to carry the patch anymore.
Fixed in gpsd-3.20