why comments may appear folded or truncated

Is it because the Comments score is too low?

Yes, low comment scores are one of the main reasons comments get folded or truncated on Reddit. It’s part of Reddit's effort to keep the most relevant or valuable content visible. Other reasons could include being flagged by users, breaking subreddit rules, or even Reddit's spam filters acting up. If you're seeing this on your own comments, try engaging in subreddits where you already have a good reputation or building karma to avoid this issue.

Some subreddits use crowd control settings that cause this. Below are different crowd control levels:

• Lenient: Comments from users who have negative karma in your community are automatically collapsed.
• Moderate: Comments from new users and users with negative karma in your community are automatically collapsed.
• Strict: Comments from users who haven’t joined your community, new users, and users with negative karma in your community are automatically collapsed.