Prerequisites

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• Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

Note:

• Arguably, the stringification of an incidentally [psobject]-wrapped value makes more sense.
  • See also: Export-Csv/ConvertTo-Csv to better stringify complex properties #20383
• Ultimately, this is yet another manifestation of Objects are situationally invisibly [psobject]-wrapped, sometimes causing unexpected behavior. #5579 in that the way in which the calculated property's value is created involves an incidental (and otherwise invisible) [psobject] wrapper.

& {
  [psobject]::new() | Select-Object @{Name = "Groups"; Expression = { 'a', 'b', 'c' } } 
  [pscustomobject] @{ Groups = 'a', 'b', 'c' }
} | ConvertTo-Csv

Expected behavior

"Groups"
"a b c"
"a b c"

Actual behavior

"Groups"
"a b c"
"System.Object[]"

That is, without the incidental [psobject] wrapper, simple .ToString() stringification was applied.

Error details

No response

Environment data

PowerShell 7.4.0-preview.6

Visuals

No response