Ash Wednesday changes its date based on the calendar year. As you guessed by the name, it occurs on a Wednesday, and always happens right after Mardi Gras (or “Fat Tuesday,” “Shrove Tuesday”). For the year in which this article is being written, 2021, Ash Wednesday occurs on February 17. Easter falls a little earlier than usual this year.

https://www.christianity.com/wiki/holidays/an-ash-wednesday-prayer-to-remember-gods-merciful-love.html