Found here: https://goodbyedpi.com/2024/05/27/how-does-goodbyedpi-work/
Packet Fragmentation
Packet fragmentation involves breaking down data packets into smaller fragments. DPI systems often struggle to reassemble these fragmented packets, leading to content inspection and filtering failure. GoodbyeDPI takes advantage of this weakness to bypass censorship.
TCP Window Size Reduction
GoodbyeDPI also uses TCP window size reduction. By reducing the TCP window size, GoodbyeDPI limits the data transmitted in a single packet. This forces DPI systems to handle multiple smaller packets, increasing the likelihood of evading detection.
DNS Spoofing
DNS spoofing is a method where GoodbyeDPI manipulates DNS responses to bypass censorship. By altering DNS responses, GoodbyeDPI can redirect traffic to its intended destination without DPI systems blocking it.
It’d probably make it harder to deny some packets on ISP’s side if they block specifilc thiings like torrents. To mask this traffic under the one sent to Facebook, I guess it should be a bit more specialized.