The simple answer is no, GLP-1s do not cause thyroid cancer in humans.
Early studies demonstrated that when rats were treated with dulaglutide and other GLP-1 therapies many developed a very rare and lethal thyroid cancer called medullary thyroid carcinoma. Rats have very high levels of GLP-1 receptors in their thyroids. These are not present in human thyroid cell.
The early concern that GLP-1 causes thyriod cancer has lead to extensive investiagtions and studies looking at this issues and to date there has been nothing to suggest a concern despite millions of people being treated with GLP-1 therapies around the world.
It is not recommended to use GLP-1 therapies like Trulicity and Victoza (liraglutide) if there is a family history of medullary cell carcinoma of the thyroid or Multiple Endocrine Neoplasia Type 2 (MEN 2).