Samsung S20 FE 5G - Confusing discount!

This is £420, but there's a £100 off voucher valid until the 16th of May to bring it down to £320 delivered.

I think it's only 1 voucher per amazon account.

https://smile.amazon.co.uk/gp/product/B08FTBSHKW/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&th=1

EDIT: Actually hold up, I ordered this with other items and all I saw was £100 off the EX VAT rate:

So it was showing as £250.50 EX VAT for this item and then I didn't really pay attention to the import fees and just assumed it was the 23% Irish VAT rate on top which actually would have brought it to €364, not €380 (which I calculated based on it being £420.60 minus £100 = £320.60 (which I just rounded up to €380, even though it should be €320.60 minus 20% UK VAT (divide by 1.2) = £267.17 + 23% Irish VAT (£61.45) = £328.61, so about €387...

However, I noticed the charge on my card was higher than I was expecting so put it in the basket of another amazon account (since I couldn't with mine since the discount is only 1 per amazon account) and I again got the above discount applied showing as £250.50 after the discount was applied, but then, when ordering only this item, with free delivery and discount applied, it's showing as this:

Which is actually working out to be €413 🤪

So I don't know what's going on here now, if some of that "deposit" amount will be refunded or what. Is it DUTY they are applying on top as well as the Irish VAT? I haven't ordered much from Amazon since Brexit, and I think this is the first thing over €150 (I believe the amount that DUTY is applied after) that I've ordered since Brexit.

Either way, the figures seem to be all over the place with Amazon, appearing to discount the £100 off the EX VAT rate, then appearing to discount it on the order summary part, off the VAT inclusive rate, but then there's import fees and deposits it's discounting it off too!.