According to vim help, https://vimhelp.org/terminal.txt.html#t_CTRL-W_CTRL-C <C-w><C-c> will forcibly end the terminal job.
I've been unable to disable this; I've attempted many variations of the following:
:tnoremap <C-w><C-c> <Nop>
Unfortunately, what this achieves is quite strange; the mapping indeed makes a simultaneous combination of <C-w><C-c> do nothing; however, if one waits for several seconds after <C-w>, then decides to hit <C-c>, somehow the t_CTRL-W_CTRL-C still triggers, and promptly destroys my terminal.
How can we get this to work? Thanks.