After updates-testing repo got disabled I just re-enabled it, and seemingly both distro-sync and update do the same thing now (no updates with either after clean).
sudo dnf config-manager 'setopt' 'updates-testing'.'enabled'='1'
sudo dnf repolist
fedora Fedora 41 - x86_64
fedora-cisco-openh264 Fedora 41 openh264 (From Cisco) - x86_64
rpmfusion-free RPM Fusion for Fedora 41 - Free
rpmfusion-free-tainted RPM Fusion for Fedora 41 - Free tainted
rpmfusion-free-updates-testing RPM Fusion for Fedora 41 - Free - Test Updates
rpmfusion-nonfree RPM Fusion for Fedora 41 - Nonfree
rpmfusion-nonfree-tainted RPM Fusion for Fedora 41 - Nonfree tainted
rpmfusion-nonfree-updates-testing RPM Fusion for Fedora 41 - Nonfree - Test Updates
updates Fedora 41 - x86_64 - Updates
updates-testing Fedora 41 - x86_64 - Test Updates
It seems like to avoid this in the future, if updates-testing gets disabled before a new official release version/date/Go ISO, re-enable it.
Is there any chance of updates-testing getting disabled again? As I understand this is only a thing during pre-release versions when the testing repo gets intentionally disabled, implying RC and final/RTM ISOs will keep updates-testing enabled after that point if the user enabled it? Or will it happen again between this point and when F41 officially releases?