So far I haven’t done anything apart from Share from Google Maps Web and Open with OsmAnd~. I have not faced such errorneous behaviour. Proabably because I have never shared a pin, and always shared places which I have found through Google Maps.
I will try more with pins and custom locations, and let you know.
See from the notification settings if this notification is categorized under some head. And if the category is not catch all, you may disable notification for that category. Otherwise blocking all notification or switching to alternative app would be the last option.