I had this happen when I had pneumonia. When I woke up one morning I coughed up about 1/2 cup bright red blood. It was difficult to tell whether it was coming from my nose, chest or both. I went directly to the ER. They stopped the bleeding with nebulized txa (tranexamic acid). I then had a bronchoscopy to determine the cause. It turns out I had a fungal infection and MAC. The cause of coughing up blood or hemoptysis may or may not be serious. Regardless of the amount of bleeding you should contact your doctor. Recommendations per Cleveland Clinic:

If you're coughing up small amounts of blood for longer than a week, make an appointment with a healthcare provider. They’ll determine what’s causing your hemoptysis and get you the necessary treatment.

Seek immediate medical attention if you’re coughing up more than a few teaspoons of blood, if you’ve been coughing up blood longer than a week or if your cough is accompanied by other symptoms including:
Fever.
Chest pain.
Night sweats.
Shortness of breath.
Rapid or severe weight loss.
Dizziness or light-headedness.
Blood in your urine (hematuria) or stools.

It was recently suggested to take pictures of the bleeding to help your doctor determine the severity. Hoping and praying that it’s nothing serious.