aku-no-homu:

25話の作打ちで宮島さんが言ってたやつその①(本人に許可もらいました) and 25話作打ちその② by artist/LWA animator @gomi_dame332

English summary via /a/:

Akko and Amanda’s group formed an “Akko might fly today” club. Akko
fails every time and they just fool around. Akko usually doesn’t tell
Diana to come because she doesn’t like failing before Diana and because
Diana takes things too seriously in different ways. Diana was invited
this time because Akko felt she was going to finally fly. Diana, taking
things too seriously, thought she needed to prepare
pastries and sandwiches and tea because she was invited so she got up
early to get everything ready.

Miyajima Yoshihiro seems to confirm this as canon here: https://twitter.com/miyazima1987/status/880041542743871489