You may see fewer tweets from accounts you care about in your timeline, for instance, because individuals who choose not to pay for Twitter Blue will become less visible on the site.

It may become harder for most users to discern real people from phony accounts. If check marks are removed from the accounts of celebrities who are unwilling to pay for Blue, for example, it could become difficult to distinguish their accounts from impersonators.

Mr. Musk has said only posts from paid accounts with blue checks will be visible in Twitter’s “For You” tab, the default timeline of tweets that the platform shows you based on your interests. The only exception, he later said, will be posts from nonverified accounts that you already follow, which will continue showing up in your timeline.

All of this means it is likely to become tougher to discover posts from accounts without the blue check marks. For example, if you follow lots of news about sports and a nonverified account tweets some sports-related news, you won’t see it in your timeline unless you already follow that account. In the past, you may have found that content purely because it went viral.

One caveat to these likely changes is that Mr. Musk is not known for always following through on his public intentions. So parts of the check-mark policy could change as Twitter rolls it out.