Are the reviews from ARCs verified Amazon reviews?

No. Since readers receive a complimentary copy of your book, they do not have to purchase your book on Amazon. Thus, when they leave an Amazon review, it will not have the Verified Purchase tag. That being said, readers occasionally do buy the book even after getting an ARC, and their reviews show up as verified purchases.

I hear Amazon is removing unverified reviews...

We've heard Amazon is cracking down on low quality reviews, AI generated reviews, suspicious reviewer accounts, and suspicious author accounts who try to game the review system (ex. by asking friends or family or paying reviewers). We have not heard that they're indiscriminately taking down all unverified reviews.

From our side, we abide by Amazon's community guidelines. We also offer a way for authors and publishers to vet readers who can access their book. This enables you to approve readers who write high quality reviews which are less likely to be removed by Amazon in future.

Lastly, thousands of unverified Amazon reviews get posted via BookSirens every month and we haven't been hearing any complaints from other authors about them being removed. This leads us to believe that the removal rate is low enough to not be noticed.

Since we're not affiliated with Amazon, we cannot predict whether their systems and policies will change in the future.