Some free sites that offer comics similar to manga include Webtoons and Tapas. However, keep in mind that the quality and quantity of content can differ, and not all may have the exact style you're looking for.
For a great manga reading experience, you could try Viz Media or Comixology. They have licensed content and reliable servers. But remember, always respect copyright and choose legal platforms.
Well, there could be a variety of reasons. Maybe a cyber attack, or the sites didn't comply with certain regulations. Sometimes it could just be a glitch in the system that needs to be fixed.