This would usually happen because of skeletons. If the skeleton shoots a creeper when the creeper isn't targeting a player, It would most likely explode. Because of this, creepers would explode holes in a wall that surrounds a village and puts the village in danger. Raiders got through the wall hole which was caused by creeper exploding after accidentally being shot by a skeleton trying to shoot an iron golem. What I mean by "isn't targeting the player" is that the creeper doesn't detect the player.
Comments 2
Thank you for your report!
We're actually already tracking this issue in MC-74908, so I resolved and linked this ticket as a duplicate.
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I'm fairly certain this is normal behaviour since I've seen it (and exploited it) in previous versions.
Recommendation for your villages - add external bamboo grove and prickly bush "walls". It works quite well.