tip of the ice cube

Based on tip of the iceberg, with an ice cube being a comparatively tiny object.

tip of the ice cube

1. (humorous) The first aspect of an insignificant or exaggerated problem or situation.
   • 2022, David Scott Diffrient, Comic Drunks, Crazy Cults, and Lovable Monsters, page 93:

     In fact, this is “just the tip of the ice cube,” for he also has to worry about the charges that have accrued at the camp's other watering hole, Rosie's bar.

   • 2021, Iain McCaig, Shadowline, page 67:

     “Come on,” he said, “This is only the tip of the ice cube. Let me show you some of the stuff that never made it to the big screen.”