Steps to Reproduce:

Check the following diffs:

https://en.wikipedia.beta.wmflabs.org/w/index.php?title=User%3ARYasmeen_%28WMF%29%2Fsandbox&type=revision&diff=459087&oldid=459086

https://en.wikipedia.beta.wmflabs.org/w/index.php?title=User%3ARYasmeen_%28WMF%29%2Fsandbox&type=revision&diff=459088&oldid=459087

https://en.wikipedia.beta.wmflabs.org/w/index.php?title=User%3ARYasmeen_%28WMF%29%2Fsandbox&type=revision&diff=459086&oldid=459085

https://en.wikipedia.beta.wmflabs.org/w/index.php?title=User%3ARYasmeen_%28WMF%29%2Fsandbox&type=revision&diff=459081&oldid=459080

https://en.wikipedia.beta.wmflabs.org/w/index.php?title=User%3ARYasmeen_%28WMF%29%2Fsandbox&type=revision&diff=459067&oldid=459066

Observed Results:

It seems like, when there are two of the same kind of elements/nodes placed in a document one after the other, the diff is showing the start tag/end tag of the existing one as newly added.

Depending on whether it was added before or after the existing one, it's sometimes the start tag or the end tag that seems wrongly positioned in the diff view.