I have a theory about the Tairazuma time skip and post graduation karaoke scene
This theory may or may not have been already discussed on this sub, but I saw someone mention it one of the discussion threads on r/anime and wanted to discuss it here as well. It could hint at Tairazuma ending up together, even though their relationship had an open ending in the manga.
This theory involves the 2nd ending theme song of the anime which, judging by its lyrics, is a love song and confession/admission of love (lyrics as pictures at the end). I believe that this song will be sung at least once by Taira and/or Azuma in the anime.
In the Tairazuma time skip, we see the two of them singing a song together in her car. When Azuma played the song, Taira recognized it immediately, meaning the two of them (and the audience) are familiar with the tune. My guess is that it is the 2nd ending theme song of the anime. If that is indeed the case, it would be a very big hint that the two end up together based on the lyrics of the song.
In the manga, the "credits start to roll" after the Tairazuma time skip and this song would be a smooth transition between those two scenes in the anime.
After graduation, we see the gang sing at a karaoke bar. In the previous episode of the anime, we learned that Taira regulary goes to a karaoke bar with others. When asked by Azuma what he usually sings, he didn't want her to know so he wouldn't get teased by her. What if Taira sings cheesy love songs?
In the extra after ch. 64, Azuma asks him to sing a specific song while the both of them are blushing. It seems like Taira told Azuma what he usually sings after all. All of this is observed by Tani who has become more observant during the show - he, for example, noticed the blossoming love between Yamada and Nishi and could be doing the same here.
Anyways, maybe this is all just compium and I'm way off. But I just can't shake this feeling that this song will be sung by Taira and/or Azuma in at least one of those scenes. The lyrics just fit the both of them so well. If that is indeed the case, it would be a not-so-subtle hint that Tairazuma is cannon after all.