Different default innodb_buffer_pool_size on Windows with MySQL 8.0.18
8M is a very old default for MySQL.  Yes, it is laughable.  It is much too small for any instance today.

Either that my.ini was left over from some previous installation, or it is worth a bug report.

If you have at least 4GB of RAM, set innodb_buffer_pool_size to about 70% of RAM.