animation-timing-function with transform

animation-timing-function is applied to the whole animation instead of per keyframe when the animation involves transform.
This issue is not present with other animated properties like width for example, which is correctly eased between each keyframe.

Steps to Reproduce:
1) View https://codepen.io/bali_balo/pen/1448d487d0cc3deb8cb466bafa21f914?editors=1100

Actual Results:
The third (red) bar only slows down when reaching the end of the animation.

Expected Results:
The third (red) bar should slow down when approaching the middle like the second (blue) bar, because a 50% keyframe is specified.

Hardware:
Tested on Safari, on an iPhone 8+ with iOS 14.0 - I do not own the phone so I do not have access to more advanced details.

Additional Builds and Platforms:
I get the expected results (bottom 2 bars slowing down halfway) on my desktop's Firefox and Chrome

[Smoley]

This appears to be behaving correctly on iOS 13.6.1. and the iOS 14.2 beta. I also tested on macOS Safari beta 14.0.1 and STP 115 (14.1) and in all cases I saw the expected results.

[Radar WebKit Bug Importer]

<rdar://problem/70733627>

[Alexey Proskuryakov]

I also cannot reproduce on any builds that I have. Those are newer than iOS 14.0, so hopefully it's just already fixed.

[Antoine Quint]

*** This bug has been marked as a duplicate of bug 215807 ***