The SBE TS stage builder emits the 'time' field unconditionally. This can lead to later stages having access to the field even if it was projected out. For example,

[
{"$project": {"_id": 0, [metaFieldName]: 1}},
{"$project": {"_id": 0, [timeFieldName]: 1}}
]

This does not affect 7.2, 7.3, or any released version.