The comment was made by James Brooke, managing director of London based Rooster PR. Earlier this week Harry helped launch WaterBear, a new environment focused streaming service.
The Prince, speaking in his capacity as African Parks president, spoke emotively about the need to fight climate change.
He noted each drop of water helps to relieve parched soil before asking: “What if every single one of us was a raindrop?”
Harry added: “For me it’s about putting the do’s behind the say’s, and that is something that WaterBear is going to be doing: capitalising on a community of doers.
“There’s a lot of people that say, but this is about action.”
However speaking to The Guardian Mr Brooke argued Harry made communications mistakes demonstrating the Sussexes are still “floundering” when it comes to PR.
In particular he argued it was an error for the prince to speak about “doing not saying” from his £11.2million Los Angeles mansion.
Mr Brooke said: “The mistakes they are making are pretty basic.
“None of this is rocket science.”
READ MORE: ‘Woke’ Prince Harry sparks fury with ‘attention seeking’ Covid video
He commented: “I actually think [both brothers] genuinely trying to do what they feel is right for causes that are close to their hearts.
“But what’s clear from this week is that there is no conversation between their comms teams, which is really unfortunate.
“It probably is an indication of how deep the issues do run now between them.”
Harry and Meghan caused a global sensation back in January when they announced their intention to stand down as senior members of the Royal Family.
Instead the couple vowed to become “financially independent” and to divide their time between North America and Britain.
After a brief stay in Canada they moved to California, Meghan’s home state, shortly before it went into coronavirus lockdown.
The Duke and Duchess recently purchased a new home in Santa Barbara, to the north of Los Angeles.
Last week Meghan bravely wrote about a miscarriage she suffered earlier this year for the New York Times.
Referring to her son Archie she commented: “After changing his diaper, I felt a sharp cramp.
“I knew, as I clutched my firstborn child, that I was losing my second.”