RedOctober informs me Russia has approved in February 17, 2021 a Diablo trademark that includes goods and services for mobile games (9) and computer games (41). There is another site in Russia that lists it specifically for Diablo Immortal — and shares approximately the same date some of the other Diablo Immortal trademarks around the world were filed in (at the end of September 2020).
The first country to approve and register the Diablo Immortal trademark was México.
The second country to approve and register the Diablo Immortal trademark was United Kingdom.
The remaining countries are listed in this article — United States, European Union, Australia, New Zealand, China and Canada.