Memory card problem with the mobile phone?

I have the following problem:

Since I have my phone (Huawei P9 lite, for about 1 year) I have my 4 GB memory card in it (from Sony). But since I needed more memory, I got a 16 GB card from SanDisk. However, after a short time it was said that this defect was and I should reset everything, which I have done. This problem has occurred again and again and I switched back to my old memory card. There were no problems with this.

Now I have again brought a new memory card (again Sandisk 16 GB) and now the same problem occurs again as last time.

Unfortunately, I only took pictures of my vacation on the memory card when it was still working at the beginning and now they are somewhere on this memory card and I absolutely can't access it anymore, neither on the mobile phone nor on the laptop.

Now my question: What is going on and why can I just put the 4GB memory card into my phone without any problems? And how do I get my pictures back?

It may be that your phone only accepts 4GB memory cards and these are broken. Have you tried the 16GB card before in the laptop? Was there already an error message?

Do the SD cards work on a different device? Another smartphone or on a PC

If so, you could format the SD card with different file formats. For testing it is best to take FAT32.

If not, removing the partition table might help and then reformatting it.

Testdisk would be good for that.
Testdisk → your data carriers → Intel → Delete
https://www.cgsecurity.org/wiki/TestDisk_DE

If the SD card does not run on any device at all, it may also be that the SD card is fake.

So on the laptop it is not recognized / not recognized that even a disk is connected and on the other cell phone I've not tried…

I actually got the card from the nearest media market, so I hope it's not fake.

So according to Internet description, I can expand my phone up to 32 GB arbitrarily…

and no, I've always just tried it on the phone, went isz

Okay, then we believe the Internet, but unfortunately I can't help