There are people explicitly saying that no, it's not OK to be white - that if you're white you are automatically racist, and automatically guilty for what happened in the past. White Fragility is an example.
"It's OK to be white" isn't just a dogwhistle. (It may be that, but it isn't just that.) It's an explicit rejection of that kind of "all whites are guilty racists" baloney.
That's what makes it such an effective troll. If it was simply obviously bad from all conceivable contexts it wouldn't work. But, you are still being trolled. And, you are playing right into their game. They are getting you to sing their slogan and laughing at you the whole time.
Yes, there are some people out there in social media who have taken to hating white people for being white. That's not OK. Call it out. But, don't dance for the trolls in the process.
There's the group of anti-white haters who need to be called out. There's the vast majority of people who don't want any form of racial hatred. And, then there's the white supremacist trolls (and just plain trolls) who want to trick the vast majority of people into fighting themselves and in the process make it look like anti-white hatred is much, much more common than it really is.
"It's OK to be white" is a troll campaign that is actively being used to bait people into fighting each other and to have both sides come out thinking the other is far more racist than they really are.
"It's OK to be white" isn't just a dogwhistle. (It may be that, but it isn't just that.) It's an explicit rejection of that kind of "all whites are guilty racists" baloney.