The transparent videos displayed on the My Community page found under experiences are using the WebM Codec on Safari, however transparency is currently not supported for WebMs on Safari, resulting in very noticeable visual issues.
This video below points out the issue, along with a comparison to the page when using the Arc (Chromium) Browser.
side note, these videos appears to include unaffected mp4 sources, but they aren’t used by Safari due to their specified priority
Browser Information: Safari 18.4 on macOS
Page URL: https://create.roblox.com/dashboard/creations/experiences/*********/community