The grease is for waterproofing…..

“There is a myth floating around that putting dielectric grease into electrical connections can cause them to fail because the grease gets between the metal. That’s not true.
Although the dielectric grease does insulate the metal and wiring from external invaders, the contacts are tight enough to still maintain a connection, the grease is just displaced. That said, you do not need to squirt huge globs of dielectric grease into your connectors as you see in some videos out there.”

https://www.thedrive.com/maintenance-repair/39173/dielectric-grease

https://www.flickr.com/photos/jonathanjenkins/