Here is a bit more information on what and when this team came up with this explanation that many people did not even think of:

In 2009 French astronomers observed what was thought to be a weak radio signal coming from the exoplanet HAT-P-11b, a “mini-Neptune” about five times bigger in size than the Earth and 26 times more massive. The following year the French team made an attempt to locate the signal again, but was unsuccessful leaving the phenomenon unexplained.

The St Andrews team set out to solve the mystery. Gabriella Hodosán, the Life, Electricity, Atmosphere, Planets (LEAP) Project PhD student leading the study said: “We assumed that this signal was real and was coming from the planet. Then we asked the question: could such a radio signal be produced by lightning in the planet’s atmosphere, and if yes, how many lightning flashes would be needed for it?”

There are some related videos on this topic as well and the comments are very spirited.  Feel free to write your ideas about this theory and check back as more updates come in from that team!