Ranking sudden spike up then back down

A new keyword I’m trying to rank for has been holding steady at rank 40 for a month. I’ve started building links and then saw a sudden spike up yesterday to rank 18.

After waking up I checked the rank again and it went back down to the 40 range it’s been sitting on for a month. So this keyword jumped up 22 spots and back down in the span of 24 hours.

Would this be considered a Google Dance? Is that even still a thing? I don’t know if I should see this as a good or bad sign. Thanks for the help