Severe decrease in damage, slightly faster healing.
Brigitte’s non-healing functionality is the entire reason you pick her. Brigitte’s ability to function as a tank is to create space with her presence, similar to pre-nerf Roadhog. Similar to Roadhog’s nerf, you’re taking away the majority of her damage and very slightly increasing the rate she heals. Similar to Roadhog’s nerf, this can’t end well for the game.