So awhile back I was play around with event triggers and the versions of the game
Something I noticed before stuff I mentioned in the past
Windows and Mobile (android)
If you close the app before you start level 20, you will always trigger the "new store" pot of gold and the pig. If you just play through it seems random if it will trigger.
Windows
I have not seen the UFO or Party boosters tutorials (4 free boosters) you used to see around 100ish in multiple runs to 100.
Mobile (android)
I did see the UFO and Party booster tutorial but in two runs the levels they showed up on were different ir UFO 92 in one run and 89 in the second one as example.
It all seems kinda random even for as random as this game can get event wise.