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.
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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.