Truthfully, you should probably always do a clean install like that whenever possible. You get rid of bloat and likely wont get the issues you have now.
For some reason the Mojave clean install leaves an “Untitled” mounted disk on the system’s desktop, which you can simply eject. It is not the USB drive I used to install it, as that was separate.
Also on a clean install, I have experienced:
During iCloud login - “Unable to login to iCloud”, however upon going into System Prefs, it was logged in, but random features such as iCloud Drive and Keychain were turned off.
Dock still pops up randomly when switching between full screen apps.
FaceTime seems to disable Wi-Fi calling on every reboot - the option to receive calls when your iPhone is nearby is still enabled, but the Enable Wi-Fi calling prompt keeps coming back. Also there is a graphical glitch with the Enable button when you do turn it on (it overlaps the level of text below it until you quit FaceTime and open it up again).
With FileVault enabled, after a reboot at the user login screen, the user’s icon is a blank (and misaligned) silhouette placeholder, however the separate Admin account shows the correct user icon.
Full screen apps do not properly adjust their transparent background to the default dynamic desert wallpaper as it changes throughout the day. Taking the app out of full screen and back in will adjust it, but I feel it should do this automatically as your background changes (I am aware this has always been a characteristic of full screen apps when you change your wallpaper, but if they are going to make a big deal out of dynamic wallpapers, they should make it work right).
The iOS app kit apps (Home, News, etc) are randomly very, very slow to launch. Sometimes they take just a few seconds to open, sometimes it is ~10 seconds.
Booting is much slower with FileVault enabled, compared to HS, and flashes briefly to an Apple logo screen which it also did not do in HS. This may be some (security) change to how FileVault/APFS works though.
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No doubt most of these “issues” will be fixed, but I can definitely feel a performance hit compared to HS. I really hope they fix the dock popping up in full screen apps soon, as I exclusively use full screen and it’s driving me nuts.