Does Adobe Spark come with a watermark?

Yes, the free version of Adobe Spark does come with a watermark which cannot be removed from any videos you create.

Users do have the option to remove the watermark when it comes to graphics, but you will be encouraged by a prompt to purchase a subscription each time. The only way to gain the ability to completely remove the Adobe Spark watermarks is by paying for Creative Cloud or the paid versions of Adobe Spark.