Evangelical Protestant here.
This city is quite Catholic, so it’s all but impossible for someone 'round here to not have exposure to Catholicism (especially since local restaurants start heavily advertising “Lenten Specials” on the radio this time of year). So I’m quite familiar with Ash Wednesday and its significance.
As for my church’s attitude toward the day - our minister might retroactively mention it in passing this Sunday. Then again, he probably won’t.