Read the rules before proceeding!

Topic: "I don't like the theme." and how you can help.

etherealdruid said:
The images/Videos/Webm/Flash/etc are not working in this version of the e621 theme.
They do not load properly only displaying the image code and video code.
Please Provide us with an option for the old UI as the new UI is bugged and Glitched.

RTFM.
Your first comment is addressed in the Apr 1 news banner. Your second comment (and your fundamental confusion about the nature of the update) is addressed by the very first post in the sticky 'e621 survival guide' thread.