That chicane in Portland has often produced starts like this.
I'm originally from Portland, attended many Indycar races at the track, and also have raced on it.
The track is quite wide right there, but the chicane is tight enough that it's basically a one line corner. You can overtake going into it, but it requires cooperation from both parties.
The original track configuration was without a chicane, what is turn 4 now was turn 1. The chicane was added to reduce speeds and to add an overtaking zone.
I think that's generally been effective, but with tight fields during starts and restarts, it can create some issues.
One idea would be to bypass the chicane on starts and restarts. The speeds are not going to be as high as they will be on a flying lap, especially if they fly the restart green flag later in the lap.
Because of the foam blocks that they want the drivers to use in the event of straight lining the chicane, this approach would have to be rethought. But they might be able to use only painted markers on the pavement to designate those zones, possibly with sensors like they have at other tracks to determine if drivers have run wide.
I get that if drivers just behaved, it would all be fine, but I'm not sure we can expect all 24 to behave.