It depends on the equipment (environment) used.

When used in a generally distributed open system, we recommend that you obtain your company's ID from the PCI-SIG and set that ID.
Otherwise, for example, if it is used only for a specific purpose, or if it is used only inside a system that is not visible to general users, it is fine to use the default Intel (formerly Altera) vendor ID.

There is also information in the Knowledge Database at the URL link below, so please refer to it.
https://www.intel.co.jp/content/www/jp/en/programmable/support/support-resources/knowledge-base/solutions/rd07022001_158.html