Все сильно поменялось, подробнее в справке.

The problem was that our legacy Unique Events metric did not properly associate all event dimensions together when calculating Unique Events. This led to discrepancies for the following use cases:

— An event dimension was omitted from a query, like querying event category and action but not label. In this case, events were rolled up across different labels as a single event, when those should have remained unique.
— When event information was never passed to GA, like when events have no label. This was causing GA to ignore those events when returning data.

What is the solution?
We’ve designed a new metric of the same name (‘Unique Events’) and will be replacing the legacy metric with the new one. At  the same time we’re renaming the legacy metric to ‘Unique Dimension Combinations’, which will remain as a metric to  enable clients to compare the two metrics as well as to enable orthogonal analyses that can only be done using the legacy metric.

This change will take place across all standard reports, however, as we do not wish to derail existing custom analysis workflows, we will not be changing custom reports automatically for our users — in those cases the name of the metric in their reports will be updated to reflect that they are using Unique Dimension Combinations*, and users will be able to choose which metric they’d like to monitor going forward and adjust or create new reports accordingly. * For both standard and custom reports, in-product help text will cover user questions for the first few weeks after launch to assist with this transition.

The new metric by definition will consider all event dimensions (category, action, and label) when calculating unique events, eliminating the issue (Issue #1 above) of rolling up information that should remain broken out as unique. We have also forced all event fields to contain a value, and where there is no value we will place “(not set)” as the value by default. This will force the system to consider all events, regardless of missing fields, such that no information is ever omitted from query results (Issue #2 above).

The combination of these two fixes will ensure stable and accurate event reporting across all queries and tagging implementations.

So now what? What do I have to do to get the new metric?
Nothing, this new metric will be rolled out across a standard Analytics reports. You will not have to opt-in or enable this change. However, as noted above, we do not wish to alter existing custom workflows, so clients should be advised where appropriate to update their existing custom reports.