As stated in our blog post about the newer Insights data explorers (simple and advanced), the plan was to deprecate the event history tab at the end of January (Data Explorer now in Public Preview (playfab.com)). There was also a banner on the event history tab for the last few weeks it was available, calling this out as well.
The newer data explorers are full replacements for the event history. They provide the ability to see all the same data, with additional functionality for improved search.
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