Flow control, aside from being yet another sexual Unix joke, is a relatively ancient feature of terminals to control bytes, the underpaid factory workers of networking.
Most importantly, they take over ^S (Ctrl-S) and ^Q (Ctrl-Q), which send bytes over the network corresponding to Xoff and Xon, which freeze and unfreeze your SSH sessions.
Real men need ^S for their history incremental search forward. We know that ^R let you search backward in history, each successive tap going further back. ^S takes you forward.
Real men also use zsh, so let’s add a setopt noflowcontrol to our .zshrc and regain the ^S that’s rightfully ours.