Yes, Scholaread hijacks this setting:

https://forums.zotero.org/discussion/comment/491058/#Comment_491058

You could presumably reinstall Scholaread and change that setting, but I'm a bit confused (and was confused by that previous report), and it would be great if you could investigate a little. If you're saying you've completely uninstalled Scholaread from your system, it obviously shouldn't be able to change this setting back, unless it left something on your system in an even more nefarious, virus-like way.

Go to the Config Editor in the Advanced pane of the Zotero settings and search for extensons.zotero.fileHandler.pdf. If you set the Zotero reader setting to "Zotero", that setting in Config Editor should be blank, including after you restart Zotero. Is that the case for you?

This setting comes from a line in prefs.js in your Zotero profile folder, which you can open with a text editor like Notepad. Is a user_pref("extensons.zotero.fileHandler.pdf", …); with "Scholaread.exe" showing up there after you close Zotero, or while Zotero is closed? (You might have to reopen the file to see the latest changes.)

Now，Now, according to

https://forums.zotero.org/discussion/comment/491058/#Comment_491058

method, I re-downloaded ScholarRead and turned off the following options, and the problem was solved.
https://s3.amazonaws.com/zotero.org/images/forums/u9724754/38bebb39vatxokhrb5ba.png

However, I don't know where the problem is.
If you want to know more, this is the URL of scholaread: https://www.scholaread.cn/.

Good luck! Everyone

There is no such plugin, I checked. Is it possible that this plugin is not displayed in zotero, it's just a guess.
Now the problem is solved, thank you very much.