Apache Spark casually gets called Spark, and it especially gets called Spark when referring to subprojects. For instance there's Spark Core, Spark Streaming, and PySpark. https://en.wikipedia.org/wiki/Apache_Spark

BTW the trademark: https://spark.apache.org/trademarks.html

And the article refers to “spark applications”, which immediately brought to mind the Apache Spark.

The wording of this does imply they've trademarked the word Spark, but that really doesn't sound likely.

Trademarks are automatic when certain criteria such as usage in commerce are met, at least under the statutory or common law of most/all US states and some other countries with English colonial histories; certain US federal protection under the Lanham Act can also be automatic. You’re probably thinking of registered trademarks which are indeed not automatic. Both kinds are often illegal to infringe, but unregistered trademarks have fewer and weaker remedies in court.

Whenever you see the raised TM symbol, that’s claiming trademark status but not necessarily registered trademark status. The R in a circle is restricted to registered trademarks.

You can see here that Apache’s trademark for Spark is unregistered, but that doesn’t make it invalid (at least in the US and the other countries I alluded to): https://www.apache.org/foundation/marks/list/#unreg_s

Fun fact: it’s also possible to register trademarks with US states, but that’s almost always worse than doing so federally with the USPTO, and federal registration is valid nationwide. State-level trademark registration is mainly a historical artifact predating the federal trademark system, but it’s still technically available.