Current Datamines: (Updated 2024-07-24)

This information is based on data found in MY HERO ULTRA RUMBLE itself. Remember, nothing here is confirmation of anything releasing sooner or later, and is subject to change at any time.
So far datamines from UltraRumble.com have been consistently correct with releases and nothing has been wrong. Things found in the past in previous seasons have in fact released in the following seasons.
(Eg. Twice and All for One found prior in Season 2, released in Season 3/4. Mirio and Dabi's Quirk Set found in Season 4, released/releasing in Season 5.)

New Game Mode Data
Code Name: SQUAD_KINGS_BATTLE
Game Mode Name: LEADERS BATTLE
Description: 仲間と連携し\nリーダーを守り抜け！    -    Work with your friends to protect your leader!
There are JSON data files as well for this mode similarly to the existing modes that are playable in game. As of 2024-03-27, this data was removed.
Denki Kaminari Quirk Set Data
Role/Type Change currently unknown.
Quirk Skill Variant Name: ライトニング -> Lightning
Quirk Skill Variant Description: 上鳴電気の"個性"技セット ライトニング -> Kaminari Denki's "Individuality" technique set Lightning
"available_at:": 2024-05-22 13:00:00 JST This is NOT the same as a Release Date. (This has been removed since 5/22/2024)
Variant Quirk Skills unknown at this time.
This is all known Data and Assets known for this character quirk set.
Eijiro Kirishima Quirk Set Data
Quirk Set Name & Skill Unknown at this time.
As of 2024/06/19, in the assets for Projectile assets/data, there are sub folders for certain characters called "Var01". "Var01" folders and naming is generally used for character quirk sets, and looking at the characters with "Var01" sub folders, all are characters with released quirk sets and a couple of unreleased quirk sets. Characters with the Var01 folder include Izuku Midoriya (Ch001), Katsuki Bakugo (Ch002), Tomura Shigaraki (Ch015), and Dabi (Ch017). The ones that also have "Var01" sub folders are Eijiro Kirishima (Ch008) and Himiko Toga (Ch018). So only characters with quirk sets have this "Var01" folder, it is safe to assume Eijiro Kirishima and Himiko Toga are having quirk sets in development (Also Toga who we previously knew had a qurik set in development, has the previous datamined information above that also still exists in the masterdata). When will these quirk sets release? It is unknown at this time.
Thanks to Taz for bringing this to my attention to look further into.
Click here to view a more detailed post about the Eijiro Kirishima qurik set here
This is all known Data and Assets known for this character quirk set.

Quirk Skill Set (Variations) Possible Release Order List(?)
Added to MasterData as of 2024-07-24
Click here to view the detailed X (Twitter) post from HydrosPlays, listing of the Quirk Skill Set (Variations)

Skill Set names generally are named after one of the Quirk Skills in the Set. Like Shoto's quirk set name is based off his Alpha Quirk Name in the set. Shigaraki is based on the Gamma, etc. All the default quirk sets all characters have, share the name "Default" so having unique names like this points to them being quirk sets. Also is given that most if not all of them do not have default quirk names from this list at all. Another note is, Denki's quirk set data from prior that I found was ID 7 for the desc, and ID5 for the name, this list retained that Denki is ID 7, which is after Shoto's quirk set. So Denki COULD be the next qurik set we see in S7 if this list is accurate. Because the ID order of the names/descriptions are relative to the order they release. The only exception being Bakugo and Shigaraki. But those two are a bit of an outlier given Season 4 released 2 in 1 season. Seems we may not get that again and only 1 per season. So from Dabi and down, I think is a more accurate representation of the "order". That is if this is the order we get.
Note: These are subject to change at any point. The order of these quirk sets are not guaranteed to happen in this order specifically.

Unreleased Emblems