We tried on default installation of Pop!os 22.04 and we don't see such issue with auto completion popup dialog.
In our case, Pop!OS is running inside a QEMU/KVM machine, and we installed the default one  (not the NVIDIA version).

We haven't tried on Pop!OS  21.10, and neither with NVIDIA version.

The install libgtk-3 is version 3.24.33, so I don't think this would explain the difference.

Can you tell us a bit more about your environment?
- NVIDIA?
- inside a virtual machine, or no
- is it default installation, or you did installed extra package, eventually manually upgraded a few packages like libgtk-3 ? 
- I guess Pop!OS uses xorg, and not wayland as default, but do you confirm you are not using wayland?

On Linux, it happens sometime that user may have UI issue when it is not the standard installation ... and this is the main issue with Linux, there are so many different flavor and customization, this is sometime hard to support all cases. That's also the beauty of Linux to have such diversity and customization.

So far, we are not able to reproduce this auto-completion issue.
And any additional information will be appreciated.