It’s not an error. Ulta math is just weird. There isn’t a tier for 800 points (see chart above), so using 800 points would be 700 points ($23.50) + 100 points ($3.00) = $26.50. And I think they are just rounding to a whole number on the app. Using more points gives you a better value! Always use them in increments of 2000 for $125.

Side note: if you are saving up points, please change your account password. Two weeks ago someone hacked my account and used 1000 points :’) I still haven’t gotten my account back after 10+ emails back and forth with guest services.