SamMeBe

That issue that's linked refers to only shallow (1 block) water. It effects water of all depths.

@Neko while it's obviously not the end of the world if it's not put into a separate issue and therefore does not need to be a separate issue. Based on the number of issues marked as duplicates of it there is obviously some kind of miscommunication going on in regards to what that issue is referring to.
If you are so adamant about not having it as a separate issue then someone should edit the summary and description of that issue to make it more clear. (Such as adding something like "and causing FOV changes while sprinting and bobbing" to the title)

@Matthew notice how you said "caused by". JIRA has a way of linking issues using caused by for this exact reason. The change from being able to sprint in shallow (1 block) water to being unable to is one 'issue'. It caused an unforseen issue of the FOV changing when bobbing and sprinting.

@Neko there should be a way to then link the issue as caused by rather than duplicate. I know this can be done in JIRA

@Neko that issue is written improperly then. It is referring to two different things and it's only one bug. It says in the second line "You are unable to sprint using control when on the ground in one-high water. This is easily seen with the lack of FOV change clearly seen in versions 1.13-pre6 and prior." This is the main problem the issue is referring to based on the title Sprinting in shallow water is no longer possible.
What I'm bringing up deals with water of all depths. What I'm talking about is a separate issue, mentioned offhandedly at the end of that issue. In order to effectively communicate this to developers it should be made into a separate bug.
(I work on a Development + QA team, and it's best to have things broken down so that they can pinpoint the different causes and organize their sprints.)

This should be broken into to two bugs. It is talking about two different issues.

1. Unable to sprint in shallow (1 block) water

2. FOV changing while bobbing and sprinting in water

@Neko this is not a duplicate. Depth of water here makes no difference. I checked that issue before creating this one and saw that it was not talking about the same thing

I am having this problem in a singleplayer world.

I checked and my difficulty was not peaceful (my difficulty was set to normal) so hostile mobs should be spawning in low light. I went caving without torches and did not see a single mob. I spent two nights out and only saw one creeper (not a single other hostile mob).

After changing my difficulty to hard (hoping to get more mobs to spawn) nothing happened until I quit to title and reopened the world. At this point more hostile mobs spawned. When I changed the difficulty back to normal, quit and reopened the world I was once again unable to find hostile mobs.