Cavallo came out as gay, with Adelaide's support, in 2021, becoming the world's first openly gay active professional male footballer.
He departed the club in May to move to the UK after limited game time in his final two seasons and currently plays at lower-tier Stamford.
Cavallo, 26, didn't feature last season and was an unused substitute eight times under then-coach Carl Veart, playing his last Reds game in February 2024.
He also played just four games in the 2023-24 campaign, having suffered a hamstring strain after recovering from an achilles tendon rupture.
But in a damning post on Tuesday morning - three days before the Reds' Pride Cup against Melbourne Victory - Cavallo hit out at Adelaide.
He alleged his playing opportunities in his final years there were "blocked" because of his sexuality, not injuries, and said teammates had mocked a photo of he and his partner.
"It's taken me a while to digest how my time at Adelaide United ended, but I think the fans deserve honesty," Cavallo wrote on Instagram.
"Leaving the club had nothing to do with football. Decisions were made by people in power that blocked my opportunities, not because of my talent, but because of who I choose to love.
"Under the new management, it became clear that I wasn't allowed on the pitch because of politics.
"It's hard to swallow when I realised my own club was homophobic. I was angry because people thought I was sidelined based on injuries, when in reality, it was internal homophobia that kept me on the bench.
"I stayed professional, kept my head down, and worked hard every day which I'm proud of.
"Yet no matter how much I produced or improved, my contributions were continuously ignored. It brought a lot of negativity and affected my wellbeing as a professional footballer."
Cavallo said the experience made him question whether coming out had been the right decision.
"This was exactly the fear I had about coming out, seeing prejudice affect my career in modern day," he said.
"For the first time, l actually questioned if I should have kept my sexuality a secret. This brought up fears I had about coming out publicly, that being myself would affect my career.
"I felt incredibly isolated and wondered if I'd made the mistake of sharing my story.
"I felt things going backwards, not just on the pitch, but in the one place l thought was a safe space and after seeing a group chat of teammates mocking a picture of me and my partner only added to this heartache.
"This fresh start in the UK has helped me breathe again and I hope I can fall back in love with the sport that means everything to me.
"Despite the way it ended behind the scenes, I refuse to let it ruin my connection to this city. Adelaide is where I found my wings."
AAP has contacted Adelaide United for comment.
Lifeline 13 11 14
Fullstop Australia 1800 385 578
20°C