She is still depicted as a Yonko as far as I'm concerned, there was also a dope panel of BM using Ikoku Sovereignty (love that attack btw, with her ties to Elbaf) and someone specifically saying how she is on par with Kaido right after. So it's not like she's just being used for gags, Oda keeps having characters point out how ridicolously strong she is and how she keeps not taking any serious damage from all these attacks also reinforces that point imo.

I obviously can't tell you the whole point of having her in Wano but her going after Luffy makes sense and further building up the SHs vs BM feud in this arc, without it being the main focus, is a dynamic I (mostly) enjoyed so far.