Hi @Putactu
Personally, I would flag a review containing a link, or also an invitation, to check an Instagram profile, as self advertisement (spam), and I would ask for removing that review. The review should be genuine, reflecting your experience of the place.
Please check Tips for writing great reviews and Maps User Contributed Content Policy
In addition, the Format Specific Criteria is very clear: Don’t use reviews for advertising purposes. This includes, but is not limited to, posting email addresses, phone numbers, social media links, or links to other websites in your reviews.