I had purchased a set of 10 earbuds for $10 or something. They were horrible, like really bad with muffled sound. It had a card that if I post a review they’ll give me $15 gift card.

I wrote a review with how bad they were and also made a note of the $15 gift card offer. Last I checked my review was not deleted and it was available. I don’t think it made any difference though since the product is full of 5-star reviews claiming they are audiophile quality earbuds.

Just curious if you had also reviewed the hub or just that it had a gift card offer?

I had a similar situation (with a pair of $25 earbuds). Amazon took my review down for "promotion", presumably because I included a picture of the card with an email address to contact if you wanted to be compensated for your review. Probably 75% of my deleted review was about the item itself.