As per platform support guide 12.2.1 is supported in Pega 7.3.1. There are conflicting responses in community on if it higher versions that are not in the guide are supported.
Weblogic compatibility with Pega 7.3 | Support Center -Not recommended
Is Weblogic 12.2.1.3 supported with PRPC 7.2.2 ? | Support Center - Supported
Can Pega support an upgrade to weblogic 12.2.1.4? Is it recommeded?