According to 27th March, 2025 update, from 28th April, 2025, a GitHub Individual user or organization can have maximum of 100k repositories in their account. After crossing 50k, a warning or alert will be shown that they are crossing their limits.
Reference of official GitHub Changelog: https://github.blog/changelog/2025-03-27-repository-ownership-limits/
Great to know the exact number, many of us have this confusion since using GitHub that what is the exact limit of repositories. So, we can say that, it is nearly unlimited.