The persuasive technique that is being used here is name-calling. This means that this cereal company is using, usually fake news and no evidence to say bad things about the rival company, disregarding whether it is actually true or not. People will see this cereal ad and believe it, regardless of whether there are any evidence to prove the claims.
The persuasive technique that is being used by Niko while
analyzing a cereal advertisement that suggests a rival cereal brand uses
artificial ingredients and an excess amount of sugar is called name-calling.
To add, name calling is abusive or insulting language
referring to a person or group, a verbal abuse.