I'm an affiliate marketer and trust me, you can earn a lot more than pennies! Many companies pay 10-15% of the purchase price. She could be earning 5% for every swipe-up for Ebay, between 2-10% for any Amazon swipe-ups, not sure what B&M or Home Bargains would pay (trust me, almost EVERY company has an affiliate programme - look at the bottom of a company's website and there's usually a link to it). I work with about 2 dozen companies who are all registered with a company called A-Win. You join A-Win and find the products/companies you want to promote, then apply to be on their register. They will check out your website (or in Sophie's case, her Instagram) to see what your reach is, how much traffic you get to it (engagement on Insta) and then decide if you'll be a good match for them.
And don't forget, once you swipe up on one of her Ebay links, cookies will be stored generally for 30 days, so anything you buy for the next 30 days SHE will be earning money from YOUR shopping, regardless of what you buy! You could be furnishing your house and she'd earn commission on it! So if you don't want the person to earn from you, clear those cookies regularly OR swipe up and screenshot the page, then purchase it using a different device.
If someone like me can earn a bloody good income from Affiliate Marketing, honestly, Sophie will be raking it in. Not pennies, but hundreds of thousands of £££££ a year!
(Hope it's ok to mention this but Nikki from Westholme, who is often spoken of in another thread, did a video a few weeks ago all about how affiliate/ads work on Instagram and also how the cookies work and she saved it in her highlights - definitely worth a look if you're a bit unsure of how it all works!)