Found it!
Some Trump supporters have been waking up, yeah. “Don’t expose your back, because Trump does not have yours,” one user on a pro-Trump social media group wrote. “And he never will.”
The original report is no longer live but it’s been archived:

'He Betrayed Us': Why Trump's Call To Protest Is Flopping
The vast majority of pro-Trump online groups seemed to shrug off the former President's rallying cry