It was the spark that started the online culture war that metastasized into the real world and brought about the post-truth era we are now living in.
Who knows whether it was a symptom or a cause. Either way it marks the beginning.
It may have been when you noticed it but it wasn’t the spark.
If there was an actual spark, it was the 2016 election as this was the first time when all the disinformation, professional troll farms and Russian influence truly came into play on a world changing scale.
But there was splintering of online communities and the death of nuance for years prior as well. Twitter contributed a lot by giving voices to everyone, and promoting those who’d shout the loudest. Facebook and its nasty algorithm also greatly contributed to all this (thanks, everyone who worked there, for the world we have now… hope you’re proud and putting all that ad-sponsored salary to good use).
Culture war was brewing long before, it just got amplified more and more.
I will admit that GG may have been a symptom, but I don't think it was the cause. The cause, as such, was the interblag and incorporation of advertising corrupting touch into everything.