Technical Perspective | How easy is it to implement BTC double payment with the RBF protocol?
On December 18, the portal Bitcoinbch.com issued an informal notice explaining why merchants who accept BTC should switch to BCH: "Dangerous flaws" were discovered in the BTC software. The issue is related to the length of the confirmation of the BTC-based RBF agreement, which provides individuals with the opportunity to double spend on merchants. Bitcoinbch.com CEO Hayden Otto double-pays merchants in Australia to prove the difficulty of performing the process outside.
If you want to know about Otto's content about the dual payment BTC test, you can watch the following full video: https://v.qq.com/x/page/r3038q97s19.html