If you run an account back up (or even the automated ones), they currently come with a column labelled as ‘TAG STATUS’ with a value of ‘TAGGED’ or I believe, ‘UNTAGGED’
There is another file in the back up which is included if you run it on demand (it’s not included in the scheduled back up), which is your nominal report. You may be able to filter this by bank nominal code and view the two side by side to know what’s linked. This includes the bank statement text (e.g. “Payment from Supplier Limited”).
There’s more information on setting up and running a back up here