TRYING TO UPGRADE TO PRO

I have had the basic plan for a few years and now need to upgrade to the pro plan. I am in the UK and it tells me the plan is £12.99 per month, but when I go to the payment area it is charging me £15.59 as £2.60 tax has been added. I am not VAT registered and have clicked that area to say so. What is this tax for? Is this right? A friend tells me I shouldn't be paying this tax through Zoom UK.  thanks.