I'm not entirely positive these are scale. They could be edema due to uneven watering?
Try dabbing, then wiping with cotton swab dipped in rubbing alcohol. That will almost always get scale insects (as well as related mealybugs) off. Important to dab first and count to 10-20, then wipe.
Also, scale infestation is often accompanied by ant traffic. Do you see any ants?
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