I reported to Wolfram Support:
"While version 11.2.0 was using CUDA paclet CUDAResources-Win64-11.2.22 (based on CUDA 8.0), version 11.3 is downloading paclet CUDAResources-Win64-10.5.0 (based on CUDA 7). I had hoped to get a paclet based on CUDA 9.1. But I get something very old."
Their reply:
"It does appear that the latest officially supported CUDA paclet is the version 10.5.0, shipped by the product by default. In the past, we have provided the customers, such as yourself, with the beta versions of newer paclets. I have reported the issues with the older paclets, including lack of support for CUDA toolkit 9.0, to our developers. They are working on releasing newer paclet, and we will update you as soon as it happens."
Please note that CUDA 7 does not support the latest GPU's. So for sure 11.3 will perform much slower than 11.2. Why they released beta paclets to 11.2 and no longer to 11.3 is a mystery.