Niantic has announced that they have temporary changed the Gym interaction distance which has been doubled.

Temporary changes to Pokémon GO: Gym interaction distance has been doubled

Trainers, As we develop ways to team up in Raid Battles from home, we’ll be making a temporary change to Gym interaction distance.

The distance from which you can interact with Gyms has been temporarily doubled, allowing you to be farther from Gyms and other Trainers as you challenge Raid Bosses. This change also allows you to spin Photo Discs at Gyms if you are within the doubled distance; however, it will not change the distance required to spin Photo Discs at PokéStops.

As we continue to prioritize updates to Pokémon GO features and experiences that make the game more accessible and enjoyable, be sure to follow us on social media, opt in to receive push notifications, and subscribe to our emails to stay updated on these temporary changes and more in the coming weeks.

Source: https://pokemongolive.com/en/post/gyminteractionupdate-20200331/