There is no such shortcut, nor menu command for "Paste Plain Text" in Safari.
There is one for "Paste and Match Style", which pastes the text in the same style as the style at the insertion point.

As you can see, its shortcut it Command Shift Alt V.
Chrome may well have different shortcuts from Safari.
Safari's cache mainly concerns web content, and is unlikely to affect menu shortcuts.
Answer from benwiggy on Stack ExchangeHey everyone
Google Docs specifically states that the key combination for pasting without formatting is Command+Shift+V when I'm on my macbook air 2020, but it doesn't work at all.I tried other possible key combinations, and I'm on a Turkish Q keyboard, idk if that would make a difference.
When I copy something and also try pasting by right clicking, the paste without formatting option is greyed out and pressing on paste does nothing either. Is there way I can fix this behaviour?
I tried setting hotkey through the Accessibility options but when I do that the pasting process gets rid of the hyperlinks which I don't want to do.
Thanks in advance.
I only noticed this happening today, but it's a shortcut I use all the time so I'm already at my wit's end. I know I can just paste it in a note and copy that or I can highlight and remove formatting, but after years of using keyboard shortcuts this one is just second-nature to me so it's driving me crazy when it doesn't work.
Right clicking and selecting "Paste without formatting" is working fine. And for a little bit Ctrl+V didn't work either, but it started working again. But Ctrl+Shift+V does absolutely nothing.
I already removed it from the keyboard shortcuts. And it works perfectly fine when I open up Chrome. I tried installing Google Drive's extension. The only topics I can find about this are with Google Sheets and that's actually working perfectly fine for me.
I'm on Windows and I have the latest version of Vivaldi.
EDIT -- I went to re-check the shortcuts again to see if I missed anything else that might be interfering and I saw that Vivaldi had its own Paste Without Formatting shortcut for some reason, and that it was blank for some reason. So I set that to Ctrl+Shift+V.
Hopefully this post helps someone else.
Try Cmd + Option + Shift + V its working for me
This happens because Safari and Google Doc Shortcuts are clashing with one another. We cannot change Google Doc Shortcuts but we can change Safaris.
Just go to system preferences, then select keyboard, go to shortcuts then go to app shortcuts on the left hand side.
Once you've done that, click the plus button at the bottom and it should open another window, in that window, change the Application from all apps to safari, then add the following text: Paste and Match Style in the menu Title. (I am taking this command from when you click edit on Safari in the top menu.
Enter the shortcut as Command Shift V
For an easy guide, I have attached an image:

I use to always just use the shortcut Command + Shift + V. But now it doesn't work and instead, I have to do one extra step of clicking Option between Shift & V. What is this change and how do I change it back? I don't use it often enough to use muscle memory for it.