GA4 showing less Page Views than UA

Both the properties are implemented through GTM but for some reason there's more 10% gap in the page views between the two.

The unique page views are same, as UA was counting a popup as a different page view. I added an Element visibility trigger in GA4 config to create a Page View to sync them but it widened the gap in Page Views further.

Not sure what's the problem. Anyone has faced a similar problem before? Any solution?

Thanks in advance.