Sugarcane can be placed underwater on sand/dirt just like above it, and can be stood in to breathe. I ignored this in older versions, but with 1.13 making water go through non-full blocks (making breathing underwater is nearly impossible), this seems a bit off.
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violine1101
migrated
Thank you for your report!
We're actually already tracking this issue in MC-125351, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.