Addendum: A number of other developers across engines and art styles also have a similar blurb on their itch pages asking viewers to “check us out on Tentacles Games” or something very similar; while there’s some level of fetish commonality with these games and the genres Tentacles Games seems to prefer, it very much looks like influence peddling rather than the same person/group branching out - you’ll notice the Patreon or store pages of some of the groups linked above link back to other games or have guest posts on the Patreon, and in turn some of these itch pages feature games that come from, for lack of a better term, inside the “Tentacles Games core network” of Godot games.
Reikodium’s games are unique in that - other than the main Tentacles Games itch - they’re one of the only devs that links back to the main Tentacles Games site rather than individual product pages, and one of the only devs with a TG link that also uses Godot.
I don’t know if it’s fair to say they’re at the “core” of this, but Strange Girl Studios is also heavily involved. While they are (were?) much more prolific, most of their content is Godot-based, they openly profess their love of tentacles, a lot of it is clearly the same art style, they seem to have republished or co-published a number of games from the accounts mentioned in the original post, and their Patreon published a post advertising one of Kannascape’s games only a couple months before shutting down. About two months ago they all but quit, citing shadowbanning from itch’s search results (supposedly over algorithm manipulation! Real shocker, huh?) as the reason. I’m sure it’s a complete coincidence that one of their only comments since was on a game by HoruBrain (linked in the first post), and that Tentacles Games published its first “demo” game just two days later. While Tentacles Games certainly predates Strange Girl Studio’s exit, it’s hard to dig much deeper into the identity of either of them; both of their websites were registered via GoDaddy and use their WHOIS protection service, which could be a complete coincidence but puts up an investigative wall regardless.