Because of the limits of systems that we use to process products, the maximum number of products in a product group is 80. If you have a product group with more than 80 products, the product group can be split into multiple product groups with a smaller number of products on each by giving the existing product group two different Variation Grouping IDs (bulk upload) or creating them in two separate Product Groups (UI).

If your products are being rejected for having over 80 products in a group, see this article on how to group & ungroup products in your catalog.