OpenSearch automatically adds search engines based on browsing the web. This can be useful for folks who don't want to spend the time carefully wrangling their own custom search operators and keywords. I like to meticulously curate those items, and find the automatic addition of other search engines frustrating. I'd like a switch to turn OpenSearch off.
I currently use https://github.com/gregsadetsky/chrome-dont-add-custom-search-engines as a workaround.
FWIW, Ungoogled Chromium adds a flag for this.
I would recommend replacing the automatic addition with an icon in the Omnibox if one is found, similar to how it works for PWA creation.
This comes up in different places on the interwebs and I too am somewhat surprised that search engines are magically added to my browser configuration. Also, Mozilla disabled Opensearch last year.
Can't Brave do the same or at least introduce a knob to disable this behaviour? We don't want to end up like IE, back in the days, hm? :-D

@Madis0 thanks for the link to the flag! Here's a patch we could consider pulling in if we wanted this feature (we'd probably do it a little differently, via our patching guidelines):
https://github.com/Eloston/ungoogled-chromium/blob/8d5cd3fce527462a707004b1c21212615e9561b3/patches/extra/ungoogled-chromium/add-flag-for-search-engine-collection.patch
cc: @rebron
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@Madis0 thanks for the link to the flag! Here's a patch we could consider pulling in if we wanted this feature (we'd probably do it a little differently, via our patching guidelines):
https://github.com/Eloston/ungoogled-chromium/blob/8d5cd3fce527462a707004b1c21212615e9561b3/patches/extra/ungoogled-chromium/add-flag-for-search-engine-collection.patch
cc: @rebron