Played on iOS, version 2025.49.50.2821.1160329. I used Poison the Waters to give all creatures -1/-1. My opponent has Queen Brahne and Sabotender (both 2/1) so they both die. Queen Brahne disappears from the battlefield, but Sabotender stays as a 1/0 permanently (until the very end of the match, as per screenshot). The card doesn’t have any effects, it was a bug.

I believe it was a visual bug only because my opponent didn’t seem to be able to interact with the card (it couldn’t attack or block). In fact, when I attacked with a Flyer, the game went straight to damage without pausing to see if my opponent would like to defend with their only creature with Reach: the Sabotender.