Control-r reverse-i-search in Bash: how do you "reset" the search in Cygwin?

I never tried making this the default when hitting Esc, but Bash uses readline for input, which accepts Emacs-style keybindings by default, so you can go to the bottom using M-> (usually either by combining Meta/Alt and > or by following the Esc key with >).

If M-> does not work because your terminal does not let you enter that, try ^G (Ctrl and G simultaneously). That is the "cancel" stroke in Emacs and usually works with readline too.

My Bash works as you are expecting. Maybe hitting Ctrl + C instead of Esc can help.

Also, you can search forward using Ctrl + S.

Ctrl + S works if it does not send a "stop" to your terminal, i.e., if "stty -a" gives you "-ixon". You can change it by "stty -ixon".

Thanks to @Phil for reminder.