There is no undo. What you might try is:

Restore Bookmark Backups

Firefox automatically makes backups of the bookmarks. These are stored in the bookmarkbackups folder.

Open the Bookmarks Manager; Press the Alt or F10 key to bring up the toolbar, and select Bookmarks. Hot key is <Control> (Mac=<Command>) <Shift> B.

Once the window is open, at the top of the page, press the button labeled Import and Backup. Select Restore. From the list, pick the file you want and click it.

The backups are stored in a jsonlz4 file named something like this; bookmarks-2016-06-29_1424_enD1GTH ya0JmicnYWg4V4g==.jsonlz4

In this example; 2016-06-29 = date created, 1424 = number of entries.

https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them

https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks

https://support.mozilla.org/kb/forum-response-recover-bookmarks-after-update

Note: As part of a bundle of toolbar changes, Firefox 84 for Windows reassigned Ctrl+Shift+B to the Bookmarks Toolbar and now Ctrl+Shift+O (as in "Organizer") opens the Library window.

How did you add your home bookmarks to the work bookmarks? For example:

• signed into the same Firefox Account on both computers and Sync merged them
• imported an HTML file of bookmarks
• some other method

If you used Sync, please disconnect from your Firefox Account on your work PC before doing any cleanup or you may wipe bookmarks on both Firefoxes at once.