Everything works as expected, it gets copied to "Jan 13, 2021" and to "Jan 13, 2022" etc. but for some reason when it's the date I set it doesn't end with the day, it gets extended to "Jan 14, 2020" then to "Jan 15, 2020" and so on. So, basically, it "jumps" to the next day as soon as a new day starts for me. Why does that happen? Isn't a reminder set to a certain date supposed to disappear when that day ends?
For birthdays, anniversaries, and other things that you want in your Calendar that should stay on the day that you set, instead of reminders use events
The above is because reminders are intended to be used for things that should not be shown before today until they are discarded / marked as done.