Where did you see wBTC at $20k? That would be a great arbitrage opportunity since you can still unwrap it (redeem/burn) for real BTC onchain. 
I guess he saw that information in WO because he is active there, and someone posted today that this token has been in a bit of a problem in the last 7 days. Honestly, I don't pay attention to any variations (forks) of BTC, not even to this wrapped version.
No, I did not see this post until now. I saw the chart in Coinmarketcap today, and I just checked again and was shocked. They manipulated the chart for an unknown reason. I am not the only guy who has seen WBTC de-pegged. It was de-pegged for almost all day and now regained the peg. The main problem is they manipulated the chart. They removed actual 24h low data and adjusted it with real BTC. As far as I know, this happened because of a multichain sell-off.
The line chart might just be showing a moving average to smooth out extreme fluctuations. If you change the view to the candlestick chart it will still show you how low the price went.
WBTC proof of reserves are published online. As long as the custodian holding the collateral isn't facing issues, like FTX was when soBTC depegged, I would expect the price to return to normal.
What if the platform is centralized shit? As I said, coinmarketcap fixed it, and you cannot find it anymore. As bullrun2020bro said, he noticed that too. I guess you missed the bolded part of my post. WBTC is available in multiple chains. This happened due to a multichain sell-off. Imagine a single chain has 10 WBTC, and someone sells 5 WBTC, and no one buys back and no orders. This will crash the price on that chain. It seems some whales played a good game. I don't know which chain it was. But many people have noticed the instability of WBTC since the 7th of June.