Many Overwatch players remember the days when the high damage-per-second hero, Bastion, had a shield and was a pain to deal with in the "Move the Payload" game mode. But few players were prepared for this new bug encountered in Junkertown where the Omnic hero can remain in spawn, and still shoot his enemies.
A streamer by the name "Adovahkitty" was playing in competitive mode as Mercy, and said "But Bastion!" in her stream. The kill cam showed that the enemy Bastion could take advantage of a new bug in Junkertown, since the hero is still technically in spawn, he is impossible to take out. No projectiles or damage of any kind can go through the enemy spawn (unless it is self-inflicted.)
The Bug Reports on the official Blizzard page show that the bug was reported in October of 2020, although no footage was offered at that time. Some replies to @adovahkitty's tweets imply that the bug has been reoccurring since the release of Junkertown, a map many players have pointed out has multiple bugs. The bugs reported have effects that affect the gameplay, with an example being a bug where Tracer can shoot through walls without being seen by the enemy.
As far as players have reported, this bug only occurs at specific points of the Junkertown map (depends on which point of the map players are on) so Bastion is not invincible at all times. For now, we can only hope that this is fixed in an upcoming patch.