Finally found a little something not working after the last stable update (2024/05/13).
The following variable seems to have been set to true (verify with cmd) :
gsettings get org.gnome.desktop.lockdown disable-lock-screen
Just setting it back to false works for me, using the following command :
gsettings set org.gnome.desktop.lockdown disable-lock-screen false
No idea how that happened. Manjaro did not change that setting and it’s still set to ‘false’ for me. 
hmmm. I worried about what I could have done by myself too. not changing the option is sure. Apart from the update, I have installed 2 new kernels and 2 benchmark apps (uninstalled since then). I’ll try to replicate that in the next days.
Coming from ArchLinux to confirm this issue is present there as well at version 46.4, running the gsettings command fixed my issue.
I checked my upgrade logs and I upgraded to 46.4 on August 5th and I noticed the issue started yesterday, August 21st. After analyzing further, I see that gnome-control-center and gnome-keybindings were upgraded 2 days ago!
[2024-08-20T22:15:38-0400] [ALPM] upgraded gnome-keybindings (46.3-1 → 46.4-1)
[2024-08-20T22:15:38-0400] [ALPM] upgraded gnome-control-center (46.3-1 → 46.4-1)
This probably isn’t specific to Manjaro.
Keep in mind this topic was created last May and there have been many package updates since then including three GNOME 46 point releases: 46.2, 46.3 and 46.4.
If you have issues on Arch, please post on the Arch forums.
I’m going to close this topic. If you can reproduce the issue on Manjaro, please feel free to create a new topic.