In this case yes, Brave's POV is that ads that are hosted and powered by the publisher you chose to read are in fact OK. Brave isn't anti-ads so much as it's anti-cross site tracking and ad serving.
Thank you and that does make sense, but I don’t believe there is as clean a line between 1st and 3rd party ads as others perhaps. A first party ad can still track and share your data.
You can presumably install whatever additional blockers you were using in a different browser in Brave if their built-in blocking (which I've found to be VERY effective) is not enough for you.
I was unable to find an open source ad blocker for Brave, and the Brave community was less then helpful when I was confused as why I was seeing ads when the homepage for Brave talks multiple times about ad blocking without ever mentioning it is partial blocking.
I'm also not sure I would qualify Brave's ad blocking as "partial". It blocks all 3rd party ads and tracking by default, AFAIK. But it's not as opinionated about 1st party as some other plugins are (presumably to avoid false positives).
Switching to a privacy-centric browser and seeing more ads was unexpected for myself and I would guess other as well.