Weird suggestion completion blinking in settings.json

[ArturoDent]

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version:
• OS Version:

Steps to Reproduce:

1. Open user settings.json
2. Type something that produces completions
3. Observe that the completion, presumably the ghost completion, is blinking a dark color with unreadable text.
4. Suggestions in a code editor (e.g., javascript file) does not do this.
5. Also in Insiders only, not Stable.

Version: 1.58.0-insider (user setup)
Commit: 3e0c442
Date: 2021-06-16T05:17:51.956Z
Electron: 12.0.11
Chrome: 89.0.4389.128
Node.js: 14.16.0
V8: 8.9.255.25-electron.0
OS: Windows_NT x64 10.0.21390

[hediet]

This is a duplicate of #125123.

In todays insiders build, you can set editor.suggest.previewMode to prefix to get the behavior of the stable release. Note that it suffers the same problem, it is just less likely that the preview is shown.

[hediet]

Well, having a closer look at the gif, I actually think this is only partially a duplicate.
#125123 does not explain the moving quotation mark.
It will probably be fixed by #125742 anyway, but I think it might be a separate bug.