Just tested in 1.13 pre6 and it appears resolved! Guess the new water physics don't have this bug.
This issue is still present in 1.12.2
...It seems to have either updated itself or been fixed in 14w04a.
Same here, was just about to report this. Upboated.
Fill it with ﷽. Then see how overly long it is.
Can confirm in 1.19.4 and 23w18a