Payments and incentives to take part as a volunteer in medical research are absolutely normal practice and not uncommon.
And that is for medicines going through phase I, II, and III trials, never mind those which are already authorised by MHRA and trialled in millions of people worldwide.
So if you are going to get upset about that, you should probably look into all medicines to see if you have an ethical objection to something you’re already taking or have previously taken.
Excerpt from the HRA ethics guidance
“ 3.9 Financial or other incentives, of themselves, are not considered coercive nor present an undue inducement to a potential participant where the risks and burdens involved are those that a competent, adult participant might reasonably accept for no payment.”