SPRING 21 – ANT MIGRATION TOOL
How to Use The Ant Migration Tool to Migrate Your Java Projects?
Force.com Ant Migration Tool version 51.0 is requires Java Version 11 and later.
Spring 21 Release Note Link: https://help.salesforce.com/articleView?id=release-notes.rn_deployment_ant_migration_java_11.htm&type=5&release=230
ANT Migration Tool Guide: https://developer.salesforce.com/docs/atlas.en-us.daas.meta/daas/meta_development.htm
Earlier Ant Migration Tool versions (< 51.0 version) continue to support Java version 7 or later