The following was discussed on a Windows 10 forum, but it prominently affects NVDA users who use PowerShell:
In PowerShell 7, a message about PSReadLine will be printed. This happens if PowerShell detects that you are using a screen reader that sets system-wide screen reader active flag while running. So far, NVDA and JAWS users are affected, and initial research shows that this warning was ultimately caused by compatibility issues between PowerShell 7 and NVDA.
In the meantime, if you do need to use PSReadLine module, do either;
2. If NVDA is installed, restart NVDA with screen reader flag off (Run dialog, “nvda –no-sr-flag” without quotes). This means apps that rely on screen reader flag will not be able to detect that NVDA is running, and should be used as a temporary workaround.
I began reaching out to PowerShell engineers at Microsoft in hopes of getting to the bottom of this – finding out which compatibility issues were identified in hopes that it can be resolved soon.