Gyms in Pokemon Go are either a private location or a public location, which sometimes requires permission from a third party such as a restaurant, owner of a business, or a regular person.
There was a situation a few days ago where a Gym was shut down while Trainers were raiding it. A Reddit post appeared in which a participant in those raids explained what happened and it is a rather unpleasant event.
Because of the pandemic, many people choose to shut down their businesses or closing them indefinitely, which can mean that Gyms at those locations can be taken down. To get a Gym location, Niantic has to contact the owners of the businesses to secure a “permit” to establish a Gym there. Many give the permission, but some people do not, even if it brings more profit.
Usually, there is a time gap between the business shutting down and the removal of the Gym located there, but this leads to unpredictability of the time when that Gym can disappear.
The Reddit post was created by TheOfficeRevisited where they said that at the time of shutdown they were raiding a gym for a Snorlax. Many Golden Razz Berries and Raid passes went up in flames when the Gym disappeared entirely from the map.
While we can all agree that we should be more cautious in the future, there is still a lack of communication between us, Trainers, and Niantic as a company.
We know that Niantic is doing its best to prevent things like this, but it would be nice if we get some kind of notification before a Gym is removed from the game.