I simultaneously open Windows Settings and the Registry Editor, so that I can see how changes in the Settings are reflected in the registry. 1
- Win-key + i > Personalization > Lock screen
- Win-key + r, type
regedit, press OK.
Go to HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\ContentDeliveryManager.
- To begin with, I set all the
DWORD values RotatingLockScreenEnabled, RotatingLockScreenOverlayEnabled, and SubscribedContent-338387Enabled to 0. 2
In the Settings, I turn ON Get fun facts, tips, and more […].
Then the registry values RotatingLockScreenOverlayEnabled
and SubscribedContent-338387Enabled both change from 0 to 1. 3
Under Background, when I change from Picture to Windows spotlight,
the registry value RotatingLockScreenEnabled then also goes from 0 to 1.
As this answer hints, I don't think it's possible to have Windows Spotlight ON, while at the same time having Get fun facts OFF.
But here is a registry trick: now set RotatingLockScreenOverlayEnabled and SubscribedContent-338387Enabled back to 0.
The result is almost what the asker tries to do – the lock screen shows one of the spotlight images, while not displaying any "fun facts" on the lock screen.
The caveat is that the currently displayed spotlight image will never change – unless you force it to. 4
Have a look in the Settings.
The Lock screen shows the spotlight image as Picture.
There is no way you can achieve this by just clicking any of Windows spotlight / Picture / Slideshow.

About ContentDeliveryAllowed
I haven't figured out what ContentDeliveryAllowed does.
At one point, it seemed that setting ContentDeliveryAllowed to 0 would automatically launch Microsoft Edge on every logon, but I don't know why that would happen.
For now, I've set ContentDeliveryAllowed to 1.
1
I am on Windows 10 Professional, 22H2.
2
If the DWORD value SubscribedContent-338387Enabled doesn't exist, create it.
Right-click ContentDeliveryManager > New > DWORD (32-bit) Value, paste SubscribedContent-338387Enabled.
Set its value to 0.
SubscribedContent-338388Enabled and SubscribedContent-338389Enabled do not seem to affect anything on the lock screen.
3
Press F5 in the Registry Editor to see the changes.
4
To force a new image, in Settings > Personalization > Lock screen, change Background from Picture to Windows spotlight. Put the computer to sleep (Win-key + x > u > s) or hibernate (Win-key + x > u > h).
On the lock screen, hover the camera icon, and click Not a fan.
The spotlight image will be switched.