As an American, what shocked me in the UK was the amount of ads for sports gambling. Literally every commercial during games was for a betting site. It felt pretty gross.
You're right, it's shocking, although I think it's mainly during sports (which sports nerds already pay a fortune for to subscribe to sky sports / bt sport).
The vast majority of TV viewing in the UK is on BBC, amazon prime, netflix or disney plus, and thus doesn't contain commercials, just adverts for other shows from the same provider. The rest of the stuff is mainly aimed at old people sat at home - visited my nan today, who had some terrible channel on (channel 65 or something). Adverts were almost entirely for stairlifts and to leave money to charities in wills.
The only reason sports gambling isn't as big (or bigger) in the US is due to a historical aversion to gambling (thinly veiled piety in government), and because Major league sports orgs are still figuring out how to get the most money out of it.
Sports gambling is now quite large in states that have allowed it since the SCOTUS case a year or so ago. Still not a lot of TV ads though, more web advertising.