WooCommerce has announced that it is planning to release version 6.5 in May 2022. Any user who would want to upgrade to WooCommerce 6.5 will be required to have a minimum of PHP 7.2+.
WooCommerce 6.5 PHP Requirements
WooCommerce noted that that the PHP ecosystem is evolving rapidly and old versions of PHP that some WooComemrce users are using are not anymore being maintained.
WooCommece also indicated that it depends on third-party packages that are gradually stopping support for older versions of PHP. This is causing problems as the number of third parties that support older version become unavailable.
WooCommerce has chosen PHP 7.2 as the minimum version that WooCommerce 6.5 will support because it is the most popular version of PHP old versions that are running on WooCommece installs.
If you fail to upgrade your server to PHP 7.2+ by May 2022 or after, you will not be able to upgrade to WooCommerce 6.5 but your website will still function for older versions of WooCommerce without any errors.