Haven't been able to reproduce it yet.
KabanFriends encountered a weird glitch where a blue energy cube would stretch and elongate when being placed down.
Screenshots: https:/​/​imgur.​com/​a/​wIxcbSw
This occurred on 27/1/20, KabanFriends launched the game and played 5-5 before playing that level (5-6), and while playing 5-6 suddenly that started to happen.

Note:
This would happen almost every time a blue cube was placed, and would only happen to blue cubes.
The collision of the cube did accurately change with the visuals being stretched.
FPS was at a constant 60fps give or take at the time.
No recording was taken during the glitch.
KabanFriends nor I was able to reproduce the glitch at this moment.

Has been reproduced with luck:

This happened on a profile that has completed world 5 and manually selected and completed 5-4 with collecting the secret, then manually selected 5-6 while collecting the secret.

FPS doesn't drop below 60fps.
The extended sides of the cube didn't have collision, nor did they highlight to be picked up.
Wasn't able to get another cube to stretch in the video, but KabanFriends offers their though of maybe you have to pick up the stretched cube in order to stretch another one.

Spy Luna/LapisLuna has also encountered this glitch during their first playthrough of 5-6.

Shorter forms of cube stretching has just happened in 2-6, proving that it can happen in other levels (28/3/20).
https:/​/​imgur.​com/​a/​AYcbl3G