Almost nobody refuses to leave a review because they dislike you. They mean to, then they cannot find where, and the moment passes.
Link straight to the review box
Your Google listing is not the same as your review form. Use the direct write-a-review link so the box opens ready to type, rather than dropping people on a profile page to hunt for a button.
Ask while it is fresh
The best moment is minutes after the visit, not days. A QR on the receipt or a review button on the site both catch people while the experience is still in mind.
Offer the platform they use
Not everyone is on Google. Restaurants get TripAdvisor, software gets G2, services get Trustpilot. Showing two or three options converts better than insisting on one.