Niantic has posted a detailed blog post on the Official Pokémon GO website detailing the upcoming changes to the Raid Battle feature.

Developer Insights: An Update on Raid Battles

Trainers, We greatly appreciate all the feedback you’ve shared with us about the Raid Battle feature over the past few months. We’ve been carefully reviewing your feedback and will be making a few changes to the feature in response. These improvements will not require you to update your app, but they will impact your gameplay. Below are a few notes detailing the changes as well as a few comments from our development team:

• EX Raid Battle changes
  • EX Raid Battles will take place most commonly at Gyms found in parks and sponsored locations.
  • Trainers with a high-level Gym Badge are more likely to be invited to EX Raid Battles taking place at that Gym.
  • Trainers who have completed a larger number of Raid Battles are more likely to be invited to EX Raid Battles.
  • EX Raid Battle start times now take into account popular Raid Battle times at that Gym.
  • Trainers invited to EX Raid Battles will receive an in-game notification if the EX Raid Battle is canceled.
  • Trainers will receive Stardust and Premium Raid Passes when an EX Raid Battle is canceled.

Developer Comments: Over the course of the EX Raid Battle field test, much of the feedback we received was focused around how Trainers are chosen to participate in EX Raid Battles. When the feature first entered field-testing, the system randomly selected a set of Trainers who were eligible for the EX Raid Battle. By taking Gym Badge level and total Raid Battles completed into account, we’re able to give Trainers who actively engage with the Gym where the EX Raid Battle is taking place and those who have invested more time into the Raid Battle feature a better chance of being invited to participate.

We also wanted to address some feedback we received about the timing and locations of EX Raid Battles. First, we’re taking popular Raid Battle times at the Gyms where the EX Raid Battle is taking place into account to help ensure many of the people who are invited will be able to participate. The reason we decided to have EX Raid Battles primarily take place at Gyms located in parks and at sponsored locations is to ensure the locations are easily accessible to Trainers in the area. Over time, we’ll explore hosting EX Raid Battles at more locations, but we want to first make sure those locations are also easily accessible.

We think each of these changes will have a positive impact on Trainers around the world. With the implementation of these features, we’ll be removing the field-test label and considering this the official launch of the EX Raid Battle feature. While the EX Raid Battle field test is coming to a close, we’ll continue to monitor your feedback and look to make more improvements, as we do with all Pokémon GO features.

• Raid Battle changes
  • Trainers will now receive Golden Razz Berries for completing Raid Battles.
  • The numbers of Potions and Revives awarded to Trainers for completing a Raid Battle will decrease slightly, but the quality of Potions will increase.
  • The likelihood of receiving Fast and Charged Technical Machines for completing a Tier 3 or higher Raid Battle has increased.
  • Trainers will now receive Stardust for participating in a Raid Battle, whether they win or lose.
  • Magikarp will make a triumphant return to Tier 1 Raid Battles.

Developer Comments: We want Trainers to walk away from Raid Battles feeling like they’ve earned some amazing rewards, even if the Raid Boss flees. To help make this more of a reality, we’ve made adjustments to the quality of items Trainers receive after defeating a Raid Boss. The addition of Stardust rewards for participating in a Raid Battle will help Trainers continue to power up the Pokémon they need to take on even more powerful Raid Bosses.

Source: https://pokemongolive.com/en/post/novdevupdate-raids