What instructions did you use to transfer the data? Those logins icons don't belong to Firefox so there is no way for Firefox to fix that. Those icons most likely had some data on the old drive that contained those icon info to create those icon.

^: this is not about logins, but about website favicons.

The bookmark favicons aren't part of transferring bookmarks via Sync. You can copy places.sqlite and favicons.sqlite from the old device to the new device's profile folder.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

You can copy certain files with Firefox closed from one profile folder to another/current profile folder to transfer your personal data. Note that best is to avoid restoring a full profile folder and only restore important files that are safe to restore/transfer.

• bookmarks and history: places.sqlite
• favicons: favicons.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (encrypted logins) and key4.db (encryption key/primary password) for logins saved in the Password Manager
• cert9.db for certificates stored in the Certificate Manager
• persdict.dat for words added to the spell checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

Otherwise you need to visit each bookmark to make Firefox retrieve the favicon from the server.

• https://addons.mozilla.org/firefox/addon/checkmarks-web-ext/