The phrase "is a sign of" is commonly used to indicate a connection or correlation between two things. However, there are several other ways to express this concept in writing or speech. Synonyms for "is a sign of" include "suggests", "implies", "indicates", "points to", "signals", "symbolizes", "represents", and "manifests". These alternative phrases can help to add variety and nuance to your writing while still conveying the same idea. Choosing the right synonym can also help to emphasize different aspects of the connection being made between the two things.