Because this was put away as "insufficient information" before, even though I detailed the exact steps by which this issue can be reproduced and I really don't know what more information you could possibly want (it would be very useful if someone told us what extra information we need to provide in these cases), I will try again.

Date & Time: any
Frequency: often
World name: Cerberus (though it doesn't matter)
Character name: Lelane Lavellan (though it doesn't matter)
Class/Level: any
Party or solo: any
In-game time: any
Area and coordinates: any
Steps:
1. Change to any caster job. Astrologian has the highest chance of this happening, but Black Mage causes it frequently too.
2. Get a cast interrupted by knockback or slide mechanics, such as those from the second boss Terminus Wrecker in Vanaspati dungeon.
3. After this, sometimes robe physics "break" and get reduced to simpler animations that make any robe or cape on any job move stiffly and awkwardly, instead of nice and flowing like they should.

System: PS4(original) and PS5

Connection Specs
- Type of internet connection/provider: cable

This has been happening on and off since I started playing almost 7 years ago, and is a known phenomenon that I have seen reported by many people throughout the years. It is in fact from those reports that I determined that the likely culprit was the knockback or slide mechanics interrupting the casting. I've also seen people mention DirectX being involved, but as I'm not on PC I couldn't say for sure.

It started happening a lot again when I reached Vanaspati, which does indeed have knockback mechanics, while I was leveling astrologian by running the dungeons with a trust party. Though in the past it has also happened a lot while I played Black Mage in a regular party of other people.

The bug appears to be client-side, as others see my robes move normally. I also see others' robes move normally, the only character affected is my own. Changing areas, or loading in and out of instances doesn't fix it. It has happened on both PS4 and now on PS5.

A workaround is to log out and log back in again, but as I'm sure you understand, in these busy times with login queues up to 3-4 hours, relogging is not a feasible solution. If anything can be done to fix it, please.