The bug

When you take damage, the hearts you lost are supposed to flash white 3 times. However, If you take damage again while the health bar is still flashing, it will reset the flash animation with the same number of hearts flashing. Instead of there being 2 overlapping animations like there should be, they will be combined into one.

For example, if you take 2 hearts damage, then after 1 flash you take 1 heart damage, what should have happened is that 3 hearts flash twice, then 1 heart flashes once. What really happened is that 3 hearts flashed 3 times.

How to reproduce

To replicate, stand on a cactus. As you take damage, the number of hearts that flash will keep increasing, and will always be equal to your starting health minus your current health.