Well, unreleased episodes usually goes in the specials. I'm missing some critical info, but from what I could piece together:

• It was first announced as a series of twenty episodes of less than ten minutes.
• Ten episodes were released on Quibi in April 2020. None of the press releases I've read explained why only ten episodes were released.
• Three bonus episodes were given to anyone who entered their email at Quibi.com before April 6. It's not clear whether they were actual bonus episodes or simply a preview of upcoming episodes.
• The show was renewed for a second season in June 2020. I don't know if the second season was filmed. I've seen some alleged release dates float around (August 17, November 16) but then Quibi announced they would start to wind down the business.
• Quibi was shut down in December 2020, and Roky acquired the global rights to Quibi's content library the next month.
• Roku began streaming the series on May 20, 2021, with three "never-before-seen" episodes featuring Tyra Banks, Machine Gun Kelly (filmed around Feb 2020), and DaBaby.

Wasn't even aware of all that history. I've watched a few with the initial Quibi trial and just noticed that TVDB got more. Those press releases are all a bit funky. There are also some calling a "season 2" order and even claiming it premiering August 2020 but there is nothing on the wayback machine https://web.archive.org/web/20201207031146/https://quibi.com/shows/punkd-529/.
So with the "original" S1 listing from Quibi that means everything Roku adds to S1 is unaired/specials until they add an actual season 2 then.

The second season was released today on Roku and it features 10 "all-new" episodes but 3 of them (Liza Khoshy, Adam Devine, Lil Nas X) are listed in Season 1 on TMDb and in the show's archived Quibi page (thanks @sp1ti!).

@banana_girl said:

• Three bonus episodes were given to anyone who entered their email at Quibi.com before April 6. It's not clear whether they were actual bonus episodes or simply a preview of upcoming episodes.

I found this T-Mobile / Quibi partnership press release and it mentions the following:

Plus, until April 3, T-Mobile customers can sign up in the T-Mobile Tuesdays app for Android or iOS for early access to three bonus episodes of the new Jennifer Lopez series, “Thanks a Million” when it launches on April 6 -- that means customers get started with six episodes!

It's a different show and a different way to get bonus episodes but mentioning that it's "early access to three bonus episodes" and that "customers [can] get started with six episodes" seems to imply everyone got 3 episodes to start and the users that signed up early got the same 3 + access to the next 3. That might've been the case for this show, too.

If the three bonus episodes were indeed just regular episodes, it's likely the Machine Gun Kelly, DaBaby, and Tyra Banks episodes were unreleased until Roku acquired Quibi and released them as a part of the first season, since the episodes featuring Liza Khoshy, Adam Devine, Lil Nas X were not on Roku until today.

The only thing I can tell you is that the website did reflect what was in the app and was up to date (I subbed their web thumbnails to TVDB for the "50 states of fright" show). The Adam Devine I can also confirm to being in the app as it was one of the few I watched (most episodes were POC actors/rappers so Machine Gun Kelly would also have stood out). Early access were probably the same ones they had up for reviewers https://collider.com/punkd-review-quibi/?
I'd say with the lack of "history" the missing ones are specials?