This is meant as auxiliary to the fine answers already posted
that address the question more directly.
When you receive a questionable edit suggestion,
the true source of your advisor's concern
may well be in the surrounding content more than the grammar.
Quite often a seemingly-minor edit's underlying intent
is to clarify a distinction, for example,
or to fine tune an emphasis,
where you might do best to reconsider the wording,
not just punctuation.
This is true for suggested edits in general.
Each suggestion represents a location that itches,
not necessarily the very best way to scratch it.
All that you — or your advisor,
for that matter— know for absolutely certain
is that something caused enough discomfort to trigger a markup.
Your advisor quite likely hopes that
you will see more in their suggestions than
they had time to clarify, even in their thoughts.
If the edit in question does happen to be purely for grammar's sake,
drawing your advisor's attention to its material context
will forestall the edit while your advisor takes
a second look and possibly thinks of a better suggestion altogether.
In any case, grammar minutiae can be attended relatively comfortably
when the focus is momentarily wider.
For your once-versus-tense instance,
you could ask for an opinion along the lines of,
“looking at this sentence made me wonder
if I should reorder it to give a clearer sense of
how _____ depends/depend/depended on
(or leads/lead/led to, ...) _____.”
This comes from a technical editor who
views all forms of writing and markup as a series of clues
and who helps academic authors
spin English from international fiber.
Some of these authors are very confident native speakers,
with whom the ideas mentioned here
have been refined somewhat delicately.