Sorry for the wait (I know Global already has 2.1 now), here's a summary of the new information from the livestream yesterday! (As always, based on Persona5X_News' summary):
As expected, the Summer event's content is divided between two versions, 2.1 (Tropical Motoha) and 2.2 (Seaside Tomoko)
On that note, Summer Tomoko's name has been officially translated as "Seaside Tomoko"
Alongside Tropical Motoha and Seaside Tomoko will be the first two "Thieves' Secrets" challenges, which consist of several fights leading up to a boss fight (with multiple difficulties) designed specifically for the featured character. These challenges and boss fights will still be available after the featured character's banner ends, although if you haven't progressed it to a certain point (I believe the boss fight?), it'll be locked at first, and require a key item to unlock again. They also come with special limited-time fights that drop materials, with the drop rate increasing when certain characters are brought on your team (these do disappear once the featured character's banner ends)
Tropical Closer is getting some pretty crazy buffs in Global:
Global got the swimsuit costume for Queen in Version 2.1
Seaside Tomoko is also getting buffed as usual:
Wonder's swimsuit costume will be available in Version 2.2
It looks like the rest of Kiyoshi Kurotani's Synergy was finally added in Version 2.1
The first part of Kira Kitazato's Synergy will be added in Version 2.2
The fishing minigame and more songs for the band club were also added in 2.1, as well as Vicissitude Ink, an item that lets you customize Revelation Cards. All players also received a free 5-star weapon case
The Synergy Bond Reset feature will be added in Version 2.2, allowing you to go back and change whether you've romanced a character or not
Also, not directly mentioned in their recap, but a new roadmap was shared as well:
However, while the English version claims the new Contract system would be added in 2.1, it doesn't seem to have been, and the Japanese version of this roadmap doesn't list it at all.