Google says it can now take up to four business days to decide whether you're entitled to a refund. The previous policy statement stated that you would normally be notified within fifteen minutes of the request for the refund decision. In my experience with Play Store Refunds, I always received the same answer.
Please note that this does not affect the window for which you must request the initial refund. It stays 48 hours. It also does not necessarily affect how long Google will take to process the refund – this differs depending on the payment method. Full details about this can be found in the "how long repayments take" section of the support page.
This change is only about the time it takes for Google Issue a decision on the refund status. Here's an example to illustrate this:
Under the previous policy, you can request a refund at a Tuesday at 3pm, and Google will usually say whether you would be entitled to the refund at 15:15. The actual refund will then be processed later.
Now that you can get another decision within 15 minutes, it can take much longer. In fact, you can request a refund at 15:00 on Tuesday and not receive a decision next Monday. And, of course, the decision can be no, you're not entitled to a refund.
What is behind the move?
Google did not formally announce the move, so we don't have a statement on why it happened. I suspect it's about transparency.
Perhaps people have discovered that it took more than 15 minutes to make a decision, so Google changed the wording to reflect the circumstances more accurately. Or maybe Google has reduced or restructured the team that works on repayment processing, and this is now happening longer. It can be both.
Whatever the reason, it means that your repayments may take longer to come, if the decision on them also takes a few days longer. It's a pity.