That's a classic scenario, and you're very likely spot on – messing with your site mid-campaign can definitely throw Facebook's algorithm off. It's super sensitive to changes.
Here's what's probably going on and my advice:
Why the Reviews Might Have Caused the Drop:
Learning Phase Upset: Think of Facebook as a smart student. It was learning who to show your ads to based on how people behaved on your original site. When you added reviews, it's like you suddenly changed the textbook. Facebook might be thinking, 'Whoa, this page is different now. I need to re-learn how people interact with this version.' This can push your campaign back into the 'learning phase' or create instability.
Subtle User Experience Shift: Even if reviews are good, did they slow down your page a bit? Or maybe initially, the new layout subtly confused some visitors, causing them to bounce more quickly? Facebook picks up on all that.
Wait or Restart?
Given you had an amazing 8x ROAS initially and it's only been two days, my strong recommendation is to wait it out for a few more days, say 3-5 days total.
Give Facebook Time to Re-learn: It needs data with the new site. Two days isn't enough to confirm a permanent problem. If you restart now, you lose all that valuable learning history from when it was performing great.
Don't Overreact: Early campaign data can be a bit jumpy. Sometimes a dip is just a dip, especially with a fresh site change.
What You Should Do Right Now:
Hands Off! Resist the urge to make any more changes to your ads or your website for the next few days. More changes will just make it harder for the campaign to stabilize.
Verify Your Pixel: This is crucial. Use the Meta Pixel Helper Chrome extension and check your Facebook Events Manager to confirm that your 'Purchase' event (and other key events like 'Add to Cart') are still firing correctly on your site after adding the reviews. Sometimes changes break tracking.
Check Page Speed: Use a tool like Google PageSpeed Insights. Did adding the reviews noticeably slow down your site, especially on mobile? That's a common killer for conversion rates.
Review the User Flow: Put yourself in a customer's shoes. Click your ad, go through the journey. Do the reviews look good? Are they distracting? Do they push important info below the fold?
When Would You Restart?
If after, say, 5-7 days, you're still seeing zero sales and no improvement, and you've verified your tracking and site speed are okay.
If you had also made major changes to your targeting, ad creative, or the campaign's optimization goal at the same time as the website change. In that case, it often makes more sense to duplicate the ad set or campaign to give it a truly fresh start with the new parameters.
For now, give your campaign some breathing room. Monitor your key metrics daily to see if it starts to pick back up. Hopefully, it's just a temporary adjustment period!"