Ascribing things to omens is an act that falls under the category of shirk – a sin strictly forbidden by Allah Almighty. The Quran says about shirk: "Allah forgives not that partners should be set up with Him, but He forgives anything else, to whom He pleases, to set up partners with Allah is to devise a sin most heinous indeed" (Quran An-Nisa 4:48)."
If you've found yourself accidentally ascribing things to omens by thinking or believing that a normal event or happening in life is to foretell any evil or blessing/good and have used it as a basis to take on a decision, you should repent immediately. Indeed, Allah Almighty is All-forgiving and Merciful. The dua can be recited to ask Allah Almighty for His forgiveness if you've ascribed things to omens and want to repent.
Joy & Distress Duas
Allaahumma laa tayra 'illaa tayruka, wa laa khayra 'illaa khayruka, wa laa 'ilaaha ghayruka.
O Allah there is no portent other than Your portent, no goodness other than Your goodness, and none worthy of worship other than You.
The dua can be recited immediately after you've sinned and ascribed things to omens. Or if you've committed such an act in the past and have just realized and want to seek forgiveness from Allah, you can repent at any time you realize your mistake.
The Quran says: "Say, ˹O Prophet, that Allah says, ˺ "O My servants who have exceeded the limits against their souls! Do not lose hope in Allah's mercy, for Allah certainly forgives all sins. He is indeed the All-Forgiving, Most Merciful." – Surah Az-Zumar – 53