Ominous bottles cannot be obtained exactly as stated in the release notes

Duplicate of MC-270014.

It's not duplicate of MC-270014 because that issue is tested with Evoker captains. They aren't able to be spawned in pillager outpost and raid. Using /summon command might not summon vaild raid captains.

This issue uses pillagers and vindicators from pillager outpost and raids. This is exactly the same as the release note says: Raid Captains which are defeated outside a Raid

It seems like a duplicate to me...

Your issue describes how vindicator captains do not drop ominous bottles, which is what the issue I linked describes. Please correct me if I am wrong. 🙂

I fail to see how this is different from what MC-270014 describes. You mention in your steps to reproduce:

capture raid captains from pillager outpost/raid, moving them outside the raid(by minecart, boat, /tp command, etc.), then kill them. Only pillager captains drop Ominous Bottles.

Except for the fact that raid captains apart from pillagers aren't supposed to drop ominous bottles (per MC-270014).
In your comment you mention:

This issue uses pillagers and vindicators from pillager outpost and raids.

MC-270014 also describes vindicators (which cannot spawn in pillager outposts).

If you have experienced a bug that only covers pillagers, feel free to create a new report for that.

The release notes clearly says "Ominous Bottles are dropped by Raid Captains which are defeated outside a Raid". I don't understand why captains other than pillagers should be excluded and not drop ominous bottles.

Mojang themselves resolved MC-270014 as Works as Intended. They are not obligated to provide a reason for their decision.
Also, please do not comment on issues resolved as such.