[BLOCKING] *Usually* player's Camera Target "Y Value" flickers before arriving at correct value when teleporting (preventing seamless teleports)

Verification builds: Release_459200 (In full release of 1.2 as well)
Summary:
Whenever the player teleports, their camera bounces up and down ever so slightly. This normally wouldn't be noticeable unless you put a teleport command on a repeating command block (relative or absolute, doesn't matter). This bug prevents seamless teleportation. After some testing, I realized, by watching the F3 debug screen, that the player's XYZ position is actually correct and seamlessly updated and so is the Camera XYZ. However, on every single teleport, the "Camera Target XYZ" flickers on the "Y" value alone. This can be seen in the video linked below. Essentially, what I believe is happening is that the Camera Target Y position thinks it is supposed to be in one place, and then immediately updates to the correct location. This isn't just client side either as you can see it when looking at another player as well.
Here's the catch, it doesn't ALWAYS happen, it seems to have to do with lag and the state of your client.

Impact:
Our project is personally impacted by being unable to utilize the new floating point coordinates in cutscenes. Specifically in doing relative rotation teleports. It causes massive jitters that can be quite disorienting or even seizure-inducing.
In addition, seamless teleports are quite a staple of traditional mapmaking ever since they were introduced in java. Maps like "The Code" by jespertheend pioneered using seamless teleporting to create the illusion of non-euclidean spaces and other interesting effects.

Steps to Reproduce:
Put a repeating command block set to always active with any of the following commands or similar ones:
/tp @p ~ ~ ~
/tp @p 30.0 40 50.5 ~4.5 60
etc. (any teleport command. Can be seen most easily if you are staying the same XYZ location)
Try this a few times because it doesn't always happen.

Outcome:
The player is teleported correctly but for a fraction of a second the Camera Target "Y" value flashes to a different value.

Expected Results:
If the player teleports themselves to the exact same place that they are standing, there should be no visible motion on screen.

Screenshots/Videos attached: Yes
https://youtu.be/J2zu0GPre7k