There are a few instances where companies will automatically use nofollow links:
Blog comments: Nofollow was designed for blog comments. Many website builders, like WordPress, include the nofollow plugin as a part of your website to prevent spammy link comments. It’s the most commonplace to use nofollow links.
Forums: Forums are another place where spam sites post their links. Using nofollow links here prevents spammy comments and keeps the content authentic for visitors.
Paid links: If you’re paying for a link to be in a particular place, it shouldn’t count towards organic link traffic. Google frowns on using or promoting paid links as “organic” links.
These are a few instances where you’ll see nofollow links used. Nofollow links are a great protective measure to ensure sites don’t get spammy, and companies can interact and build relationships with real customers.