Syncplay version: 1.6.5 release 86
Python: 3.6.8
Pyside2: 5.12.3
Qt 5.12.3
If you send, or recieve a message that has a double quote " in it, {\\fscx0} is added to the message.
Examples:
" produces {\\fscx0} "
x " y produces x {\\fscx0} " y
x " y " z produces x {\\fscx0} " y {\\fscx0} " z
This might be an issue with mpv, but I'm not too sure because of this line of code and because {\\fscx0} doesn't appear anywhere in MPV's repo.
I have also found this issue in libass: libass/libass/issues/185 which may be related, but I'm not sure.