The swimming/crawling player model seems to be offset as the model is not in the middle of the shadow. Try swimming in third person view while crawling in a 1x1 gap (Swimming through a 1x1 source block and dig a tunnel.), the hitbox is the shadow and the swimming/crawling player model is behind the shadow.
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This ticket hasn't been updated for some time - is this still an issue in the latest version? If so, could you please add the latest affected version, or comment if this is no longer an issue.
Also, if there any further steps to reproduce the issue, please include them when possible.
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