As the apostles said, we must obey God rather than men. God has commanded us to first privately, in love, intervene with a straying brother/sister. If that doesn’t work, then one or two additional faithful believers should become involved. If that fails, then and only then is the entire church/assembly engaged in the issue.
I do consider context regarding such matters, normally. And online, the norms are a very robust give and take--much as one can see in St Paul's letters and in Christ's public exhortations of Disciples and Pharisees in front of others.
And, I think the topic of an exhortation is also a factor.
If I saw someone hereon exiting a bar quite falling down drunk, I'd mention it privately.
Go to them privately.
Only sweetness and light on the threads.