The option to show the tag column in the Transaction Lists through the vendor profile is unavailable, accounting. However, I've got a workaround that you can follow below.
You can pull up the Transaction List by Vendor in a Modern view to add the Tags column and check which tags are associated with each transaction. I'll show you how.
Go to the Reports menu.
Locate and open the Transaction List by Vendor.
Click Columns, and select More Columns.
Type in Tags in the search bar.
Click the Transaction dropdown and put a checkmark on the Tags available.
Moreover, you can click the Save As button to save its current customization settings and easily access it in the future. Here's an article for more details: Memorize reports in QuickBooks Online.
Furthermore, you can read through this link for future reference in managing tags and group tags in QuickBooks: Tag transactions in QuickBooks Online.
Please let me know if you need more help managing your vendor transactions and tags in QuickBooks. I'm always here to help.