When Google introduced the Pixel 3 and Pixel 3 XL in October of 2018, the Android-maker also announced that owners will be able to create custom, but official cases. When Google introduced the Pixel 3a and Pixel 3a XL in May this year, the Android-maker no longer takes customization orders. That’s the story.
The official support page says that the accessories are “no longer sold by Google”. If you insist on having an official case to protect your Pixel phone, you will have to settle for the basic fabric cases.
There could be several reasons behind this, from Google now selling not two, but four phones, to simply cutting costs. Which leaves you with two options: either go with a basic, fabric official case, or get a customized case from somewhere else. You can always skin it.