Hey Rick, if you edit a cell, and that input is still active, you can โ+Z. But that doesn't apply after the change is already entered.
If e.g. the cell data derived from an enrichment, you'll see a circular arrow to "Reset to original value".
All that said, I understand how editing can feel a bit precarious sometimes. I'll relay some product feedback here. I'm hopeful we can get more robust undo, versioning, etc. in the future.