Sian Jones produced the artwork initially for mental health awareness week.
The latest piece, which was vandalised, carries the message: 'There wouldn’t be rainbows without rain'.
It was on display on the Bridge near Shoezone, but it has now been taken down after a section of it was ripped off.
It is the tenth sign to be damaged out of about 44 – some caused by weather and others deliberately – including one that was broken with a pair of black pants also thrown over it.
Another, reading Optimism is contagious, was stolen over the 2019 Christmas period, but was replaced by Dowding Signs for free.
‘Unfortunately it’s happened to quite a few signs, since I first began this project in 2018,’ said Ms Jones, who created them as part of her Notes to Islanders exhibition in conjunction with Guernsey Mind and the Guernsey Arts Commission.
‘I understand the material used can be easily damaged, some by the wind especially on the west coast, but those in Town and on the Bridge have quite obviously been done by somebody intentionally.
‘Feedback from people since the damage though has been mixed, with a suggestion that perhaps someone was trying to take it down as a souvenir because it ripped and they then placed it behind the pole.
'Others have suggested that perhaps the culprits need support for their mental health and I’d like them to know that there are people here they can reach out to for help.’
She said she wanted those that were struggling to contact Guernsey Mind if they needed to talk.
‘It takes a lot of time and effort to create and install these boards and they provoke lots of different reactions from people,’ she added.
‘My intention though has always been to brighten someone’s day.’
The most recently damaged sign is not due to be replaced.
However, Ms Jones is due to link up with Guernsey Mind for another art series, with details yet to be announced.
‘They’ll be slightly different to the last ones, I don’t want to reveal too much yet,’ she said.
‘But we’ll look at reinforcing the boards to make them stronger.’
Currently, the artist is helping to paint one of the goats for the Autism Guernsey and the Guernsey Adult Literacy Project’s Golden Guernsey goat trail in September, alongside individuals who use the recovery and wellbeing service at the Oberlands Centre.
It will feature a design based on the 1970s children’s TV show The Herbs.