"One friend had a mother who died of Alzheimer's with zero covid symptoms but was misreported as Covid on her death certificate."
Death certificates have lines for immediate causes of death, and for contributing causes, so his anecdote is meaningless without actually seeing the certificate. And it's certainly possible, and even likely, that covid is what tipped her into death.
Anecdotes like this, especially second hand, from people who are ignorant of what they profess, is a major contributor to the misinformation epidemic destroying the country.
http://publichealth.lacounty.gov/wwwfiles/ph/media/media/rx-may2014.pdf
Underlying cause of death: Items 107(B-D) are for the
intermediate and underlying causes of death. This is the most
significant piece of information on the certificate since most
mortality analyses are based on the underlying cause of death.
Every condition listed should cause the one above it. Thus,
entering conditions in an illogical order will prompt the
Public Health Registrar to question the cause of death and
the certificate will be returned to the funeral director for
revision. A useful way to make sure the order of the causes
makes sense is to say the phrase “due to” or “as a consequence
of,” moving from line A down to the last filled-in line. For
instance, a death may be due to a pulmonary embolus, as a
consequence of hip surgery, resulting from an injury from a
fall, resulting from a cerebral infarction. Cerebral infarction
is the underlying cause of death. Multiple conditions cannot
be listed on 1 line in this section.
Time intervals: To the right of lines 107(A-D) are items
107(AT-DT) where the time intervals between the conditions
listed and the time of death are to be listed. The more precise
the time the better, but it is acceptable to estimate and
use terms such as “approximately.” If the time interval is
unknown and cannot be estimated, “unknown duration”
can be listed. Something must always be entered on these
lines next to the corresponding conditions; they cannot
be left blank.
PART II
Other significant conditions: Item 112 is where other ill-
nesses or conditions that may have contributed to the death,
but were not the direct cause of it, can be listed. Multiple
conditions may be listed here. There may be uncertainty as
to the direct or contributing causes of death, so it is up to the
physician to use his or her best medical judgment as to the
most likely causes and sequences contributing to death.