Hmm... The name doesn't show up on Writer Beware
but...
1. The only @bookshutter on Twitter has 881 followers and upon further investigation, it's the right one, which means they're lying about the amount of followers.
2. All of the social media icons at the bottom of their web pages redirect to their contact form, not social media, which is bad form.
3. I randomly looked up some of their featured authors and they're not ranking particularly high on Amazon dot com.
4. They registered their domain name on 12 June 2020, which means they reek of newness.
5. I've tried digging up website traffic stats and ain't getting much useful info, but their hosting provider is in India, for whatever it's worth, while the Twitter account @bookshutter says they're in Texas. Nothing wrong with using a provider on the other side of the world, but it adds a little extra reek to the odor
6. No Facebook presence.
So... I'd say they're not quite honest enough to be worth trying