I’m also experiencing a very similar (or related) issue.
Reproduction steps / cause:
- The problem occurs on extremely long posts (around 100,000 characters).
- It is triggered specifically by large-scale revisions (when a huge portion of the content is changed).
When trying to save such a massive edit, the backend often hits a timeout (502/504). I suspect the root cause is the Diff calculation between the old and new versions, which becomes extremely expensive under these two conditions combined.