It could be that both websites are true.
Scarisbrick is a small exchange (800 lines), so it doesn't need many cabinets. Such exchanges also seem to have a fair percentage of EO lines, both to the local village and to the remote villages that it serves.
It is therefore entirely possible that cabinet 5 is a new cabinet, built deliberately for EO lines in your village. If that is true, then the fttc-check website might not have captured the new information, while the BT Wholesale website could already be up-to-date.
Here's a third website:
https://www.telecom-tariffs.co.uk/codelook.htm
This one lists a lot of postcode, exchange and cabinet information - but importantly, it captures the "exchange-only" information very well.
Using the postcode (L40 9QB), it shows that the postcode would appear to be served by two different EO bundles, labelled "Exchange 2" and "Exchange 3". Clicking further suggests that "Exchange 2" actually serves 8 different postcodes, while "Exchange 3" also serves 8 postcodes, but a little further from the exchange.
From those pages, you can click onto the "Scarisbrick, Southport" locality, and get summary information, and then click on "all 7 fibre cabinets" to be shown a list of (not 7 fibre cabinets) but 3 cabinets and 4 EO bundles.
My guess is that your line has been put onto a new cabinet, number 5, which is probably located directly outside the exchange building. However, you might find that cabinet 4 is located outside the exchange building (serving bundles 1 and 4) while cabinet 5 has been more favourably sited closer to Hall Rd.
You could probably use the lists of postcodes garnered from the 4 bundles on that website, and feed them back into the BT Wholesale website (important: use the postcodes alone in the address checker, and pick sample addresses; the postcode checker won't be good enough). If that tells you that all the bundles are now on cabinet 5, then it is probably at the exchange. If you find some on a new cabinet 4, then 5 may be sited elsewhere.