For a comprehensive list of what was "fixed" in this specific version, the official documentation is the primary source: Release Notes & Installation Guide (UG973):
This document details the specific fixes, known issues, and new features for version 2020.2. You can find it on the AMD/Xilinx Documentation Portal Fixed-Point Library (HLS): If your query refers to fixed-point arithmetic, the Vivado HLS User Guide (UG902) Vitis HLS documentation xilinx vivado 20202 fixed
Vivado 2020.2 resolved several critical issues from previous 2020.x versions and introduced specific IP-level fixes: : For a comprehensive list of what was "fixed"
Vivado 2020.2 => Generate Block Design does not become finish xilinx vivado 20202 fixed