Apple Numbers has a 1,000,000 rows limit.

When importing a big CSV file, only the first million rows are imported. Extra rows are skipped.

Importing a CSV file with more than 1m rows
Importing a CSV file with more than 1m rows

This is a hard limit defined in the software. The operational limit is way lower. When editing a 1,000,000 rows spreadsheet with a Macbook Pro M1 16Go, the application freezes for several seconds every time I want to edit a cell.

Editing big spreadsheet Apple Numbers
Editing big spreadsheet Apple Numbers

How to get around Apple Numbers's max row limit?

Spreadsheet tools are not suited for big spreadsheets. They must keep all the data in memory so users can link any cell in their formulas. Apple Numbers is not a database and have poor performance on big listing. See our guide on how to edit big CSV files online.