My experience so far with Apple support (in short 😡): I got the third wireless case replacement. And also this one has exactly the same issue. I have tested with 8 different types/brands Qi charger mats. All the same issue. Apple wants me to travel more than 100 km to diagnose the issue again at a service center. If the first, second and third one does not solve it. Why the fourth visit will solve it? So I have escalated at Apple and I refuse to travel again without a guaranteed working solution. Then a call back appointment was made and they of course did not call me back. I contacted Apple again and after redirected to several persons at Apple, I was directed to after sales department. They will not help, because there are replaced parts they will not provide any options to solve or provide any compensation. I keep escalating the issue and the current status is that I have to wait now for a week for the next step. It is unclear what that step will be by Apple. During this week they going to investigate the issue at Apple HQ engineering what might be the cause.
Anyone which has this issue or similar, create a support incident. When there are more reports the more they will take this issue more seriously. And keep pushing. As they try many ways to get you stop complaining about the issue.