The advertisements pay for your UU feed. If you wish to stop paying indirectly for UU by checking out the advertisements, pay the fees and join UU VIP and pay directly.
It would be nicer if the advertisements were more focussed on a ukulele lifestyle, but who would be triggered by parts of the ukulele industry which UU members don't appreciate? What would we get then? Complaints about sellers who are not the seller of the day on UU?
Nothing on the internet is free anymore. In 1999 it might have been a happy thing that was about sharing all sorts of interesting information. In 2022 it is mostly just one big platform to buy your vote or transfer your hard earned cash into the bank account of a rich person who probably does not even live in your country. UU is one of the nicer exceptions, isn't it? The platform operators have to pay for hardware, maintenance and staff, they are doing that via direct subscriptions or by selling advertising space. If you cannot cope with that, you need to time travel back to before the internet existed and accept that you access the ukulele world via magazines and mail catalogues, or travel forward in time the to after the internet is long dead and you access the ukulele world via magazines and mail order catalogues.