You already have an answer for recent versions of Photoshop, but for versions older than CC 2018 which don't have that option, it's also possible to paste the text into a plain text editor such as Notepad or TextEdit, copy the text again, then paste into Photoshop. This will strip the formatting.
Edit menu > Paste Special > Paste without formatting
Or right click menu > Paste without formatting
You can hot-key it, as with any Adobe menu item, from Edit menu > Keyboard shortcuts…
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It is possible for some layers/sublayers to be in Outline mode while others are in Preview mode.
Check the eyeball icon... if it's got a solid iris, it's in Preview mode.. if the iris is vacant, then it's in Outline mode.
Toggling the View Menu for Preview/Outline will not toggle sublayers. Sublayers will stay in the mode they are currently in.
Toggling the ...