While it would have been great to see more of the character in his own movie, it’s likely the Cyborg movie has been all together shelved.
Cyborg spoke briefly on the delay in 2018, saying the movie could be expensive to make due to extensive CGI.
Back in 2014, it was confirmed Cyborg would get his own solo movie but following the poor reception for Justice League, nothing has come of that standalone movie as of yet.