The English language, the US dialect in particular, has been mixing & confusing "rim" & "brim" for decades, & I have a theory for how that came to be.
Every Boomer & Gen-X'er remembers Brim Coffee, even if only subconsciously, while Millennials & Gen-Z'ers have never heard of it.
General Foods advertised the hell out of it in the '70s & '80s with the slogan, "Fill it to the rim with Brim," before suddenly ending it in the '90s. The ad campaign was so successful, it blurred the words together.
Seriously. These commercials ran in virtually every TV show with the chance of an adult watching for decades.
Some of these commercials were captured and made it to YouTube: https://www.youtube.com/results?search_query=brim+commercial (search query link).
My generation began conflating the words, and today's generations never had a real chance to learn we were making that mistake. So now it's no longer a mistake, just evidence of the language evolving.
