I left this comment on a diff earlier today (the time is in Central Standard Time):
{F350199}
Ever since then, whenever I've gone to comment on other diffs, the default operation is "planned changes," and that comment shows up as the default text:
{F350201}
One time, Phabricator even went so far as to forcibly insert this comment into feedback I submitted for a diff (even after I had already deleted all text from the top-level comment submission box):
{F350203}