In OSC/OTH mode, the parser accumulate bytes until it fills up or encounters some end-of-osc sequence. After entering in either of these mode by mistake, for example by displaying random bytes (e.g. cat a binary) nothing would print anymore but input would still work. In that situation, being able to hit `reset` and recover a usable terminal helps. You can try with `echo -e '\xc2\x9e'` for PM