Can Google My Business overwrite Listings?
Yes it can. If you update the fields (data) directly in GMB rather than in Listings, we will not overwrite it in Listings. As per Google’s new policy, if an update is made by the owner in GMB, then Listings data will NOT overwrite it.
This logic had been implemented around December 2020 by Google. It is important to let Listings detect the field being out of sync and the directory to process the update. A good work around for this if you notice that your GMB is overwriting Listings and you want Listings to be leading again is to (to troubleshoot when your are facing similar issues) : change the hours in Listings (to any different value) > Sync > Put the correct values back > Sync again.
That way, the latest value will be ours and shall populate Google. But in any case : a best practice to share with anyone: DO NOT update fields in GMB directly (it also comes with a bit of patience, for the automation to do its job on all directories). So please always use Listings to update all data and do not use your GMB account to update the same type of data. This also defeats the purpose of Listings.