Uninstalling ReviewX does not delete your WooCommerce product reviews — they’re stored as standard WordPress comments, so they remain in your database and stay visible on your product pages through WooCommerce’s own review display.
What you do lose access to is everything ReviewX layers on top: multi-criteria breakdowns, photo/video attachments’ display styling, the filter/sort widget, review reminder automation, and any Pro features you had active. Reinstalling and reconnecting ReviewX brings all of that functionality back over your existing review data.