While Azorius Control received the Mystic Sanctuary + Cryptic Command lock in 2020, it was a rough year for the archetype to gain competitive footing because of the superior Bant (with Sanctuary + Cryptic lock) and 4 color Control decks dominating the format with Uro, Titan of Nature’s Wrath and Field of the Dead. 

On February 15, 2021, Modern received one of the biggest shake ups in the format’s 10 year history:

February 15, 2021 Banned & Restricted Announcement

Gone were the culprits that led to lopsided, unfair and stagnant games, which paved the way for the return of Azorius Control.

Post-Modern Horizon's II: Azorius Control’s Recalibration & Resurgence in 2021

Modern Horizon II came and conquered the Modern format. Not since War of the Spark has there been a shake up of this magnitude. Like War of the Spark, Modern Horizon II has recalibrated the way decks are designed, including Azorius Control. Counterspell, Prismatic Ending, and Solitude were the set's biggest impact on the archetype, but we've seen Fire//Ice be one of the best reasons to splash Red beyond Prismatic Ending and Wear//Tear.

Aside from Modern Horizon II, UW Control has gained Memory Deluge from Innistrad: Midnight Hunt, which is a better version of Fact or Fiction, but also has a similar ceiling as Dig Through Time. The archetype has also brought Spreading Seas back to the mix (Urza's Saga being one of the main reasons) and has incorporated Chalice of the Void to deal with the plethora of free and 1 cmc disruption and threats. It's also neat that Prismatic Ending gets around it!

It's worth noting that these revisions have cut into some of the archetype's pre-Modern Horizon II staples, such as Opt (Chalice of the Void), Path to Exile (Chalice of the Void), Force of Negation (Solitude), and even Snapcaster Mage (versions with Kaheera, the Orphanguard)! Other heavy hitters like Jace, the Mind Sculptor and Cryptic Command are still being played, but have been reduced in copies because they aren't as essential. This has less to do with the new additions and more a result of the tools other decks have gained to mitigate their effectiveness. Teferi, Time Raveler and Teferi, Hero of Dominaria have remained UW Control's best Walkers in 'New Modern'.

As of October 1st, Azorius Control is one of the top 5 decks in the format.

https://www.mtggoldfish.com/metagame/modern#online

Here's how it looks in 2021:

https://www.mtggoldfish.com/deck/4342348#online

https://www.mtggoldfish.com/deck/4343091#online