UPDATED: Some nice compensation and a fix timeline.
A celebration event in Fire Emblem Heroes has gone unexpectedly awry and Nintendo / Intelligent Systems is still investigating the root cause.
As part of the celebration of the 3.5 years of service of Heroes, a special "Hero Fest" banner was announced last night in a livestream. The "Hero Fest" banner features a higher than normal chance of summoning the focus heroes, and this banner was also to be the first banner where heroes added between December 2017 and August 2018 could not be pulled off-focus. However, the banner not only includes the heroes who were to be removed, but also includes previously removed heroes from launch to November 2017.
Notice:— Fire Emblem Heroes (@FE_Heroes_EN) August 2, 2020
We have detected an issue in which all 5★ Heroes that appear as focus Heroes in the Revival Summoning Events are appearing in the Feh's Summer Celebration Hero Fest. We are currently investigating this issue. We apologize for the inconvenience. #FEHeroes
UPDATE AUGUST 3: The compensation has been announced of a general gift of 15 orbs for all players to be distributed on August 11. Players who summon a unit who was not to be in the pool will receive further compensation on the 12th: one copy of the matching focus unit per incorrect unit pulled (and will be able to keep the improper unit as well). Following the banner's completion on Sunday the 9th, there will be a brief maintenance period to fix the banner and remove the improper units for players who start playing after August 9.