I have:
I personally recommend using Basic black PLA and printing at normal speed for its aesthetic appeal and fewer complications.
1st. - 3rd Prototype: VI-Wallet - Card Wallet (Prototypes) by VIVI Official - MakerWorld
VI-Wallet 66: VI-Wallet 66 by VIVI Official - MakerWorld
VI-Wallet 66 Smart: VI-Wallet 66 ~Smart by VIVI Official - MakerWorld
Firstly, this is quite common with print-in-place mechanical parts, so don't worry.
Use your finger or a tool to gently separate the top of the slider-circle from the wallet body; this usually resolves the issue.
If necessary, apply some pressure to the internal piece at the bottom of the wallet.
Still unresolved?
Two possibilities remain:
The bottom of the wallet may be fused, which can be remedied by carefully inserting a knife between the external and internal part.
Previously: VI-Wallet 66.6 by VIVI Official - MakerWorld
Cheers.