Geni exports its places improperly into GEDCOM.
Normally the PLAC tag should be places at level 2 below the event it pertains to, e.g.:
2 DATE 11 DEC 1901
2 PLAC Toronto, Ontario, Canada
Where the place is given as a place hierarchy separated by commas named from lowest to highest jurisdiction.
Geni instead incorrectly uses an address tag for this, and for the above example would produce the following:
2 DATE 11 DEC 1901
2 ADDR Toronto
3 CONT Ontario Canada
3 CITY Toronto
3 STAE Ontario
3 CTRY Canada
Geni may in some cases include the PLAC tag, but seems to do so for a cemetery name or hospital name which should is normally not included in the PLAC value (if it is, then as the lowest jurisdiction of the place).
The ADDR tag in GEDCOM is designed to be used for street addresses and mailing addresses. Programs that correctly use the ADDR tag most often use it in an address book, and not for standardized place names associated with events.
So the problem is not with Gramps or Wikitree import, but with the Geni export.
The GEDCOM page in Geni's wiki states in their Known Issues section the following:
Lots of GEDCOM files contain place information in PLAC fields. This field is copied directly into the place_name field in the address record. It doesn't populate the address fields (city, state, country, ...).
If you want the address fields populated, you need to make sure your GEDCOM file contains ADDR structures instead.
Please feel free to update this issue with instructions on how to do this in various genealogy programs if you know how.
Currently geocoding is done by city, state, country. I'm creating an enhancement ticket to have it geocode by place_name if those fields are empty.
This might be saying that Geni believes places should be in the ADDR field rather than in the PLAC field. According to the Wiki page history, this "Known Issue" was added to the page over 10 years ago, so it is an issue that they have not recently looked at.
If this is a major concern of yours, You could try the Geni community forum and raise the issue again. It was last raised by Kim Koblet in 2018. More info was requested six months later, but nothing happened since.
Alternatively, you can go to the Geni Help Center and submit a ticket and get a direct response from their customer service team.