Is it possible to downgrade to an older minor version of macOS?
Generally, no.
You would need to have made a bootable backup of the system and wipe / restore from it. Or you would need to have retained that specific build and/or an older Mojave installer layered with the delta installers to get from that lower MacOS version patched only to 10.14.5.
The combo updates are generally searchable and downloadable after they are no longer the latest at https://support.apple.com/kb/index?q=combo&amp;src=globalnav_support&amp;type=organic&amp;page=search&amp;locale=en_US
Here is 10.14.5 - https://support.apple.com/kb/DL2000