Happio won a 400 metres hurdles silver medal at the 2022 European Championships in Munich and reached the semi-finals of the Paris Olympics.
The anti-doping body did not specify the date of the breaches or their nature, but it could be location information incorrectly recorded or a no-show by the athlete for an unannounced out-of-competition test.
A provisional suspension can be given after three breaches in less than 12 months with the athlete risking a suspension of up to two years.