Better equipment inputs into the app. Most standard barbells only weigh 15kg or 20kg. Some exercises such as curls suggest a lower starting weight. An alternative warmup exercise with different movements or equipment could be a good option.
Thanks for your input! I noticed this as well. When that happens I usually just use a plate or dumbbells.
From Help Center > Freeletics Training > All about Weights Training Journeys:
“Please note, in the case where you are assigned less than 20 kg, you can use a light barbell, dumbbells, or weight plates.”