On Monday, April 27, 2020, Oracle released the highly anticipated 8.0.20 version of the MySQL database server. This release contains changes to the InnoDB redo log format which breaks compatibility with all currently released versions of the Percona XtraBackup 8.x series.
At this time, there are no known workarounds that will allow any version of Percona XtraBackup 8.x to function properly with MySQL 8.0.20.
We have identified the specific cause of the issue and are diligently working towards a new release that will safely solve this issue as soon as possible.
Reverting to an earlier version of MySQL is not a straightforward option, please read this blog post https://www.percona.com/blog/2020/01/10/mysql-8-minor-version-upgrades-are-one-way-only/