Short answer
Extremely dangerous — garlic powder is far more concentrated than fresh garlic and can cause severe anemia in dogs. Even a small amount sprinkled on meat or dips can be toxic. Keep all seasoned foods out of reach and call the ASPCA poison line (888-426-4435) immediately if your dog eats any. Symptoms like weakness or pale gums may take hours to appear.
Garlic powder — Food safety facts
Do not feed · Dogs · full breakdown on the linked food page
Concentrated allium — far more dangerous gram for gram than fresh garlic.
The full verdict, portion guidance and serving notes are collected on the Garlic powder food facts page.