Something's happening with vitality.vim under the new tmux v.2.8 -- it seems like some key sequence is being sent to Vim on FocusGain.
The trigger was indeed the upgrade to tmux 2.8 (and this may be related somehow). However, it's exactly vitality.vim, which is affected because switching from vitality to tmux-plugins/vim-tmux-focus-events makes this issue to go away.
Something's happening with vitality.vim under the new tmux v.2.8 -- it seems like some key sequence is being sent to Vim on FocusGain.
The trigger was indeed the upgrade to tmux 2.8 (and this may be related somehow). However, it's exactly vitality.vim, which is affected because switching from vitality to tmux-plugins/vim-tmux-focus-events makes this issue to go away.