Many webmaster noticed fluctuations in local search result during the Google May 2020 core update. Google’s John Mueller was asked same question related to local search impact by Google update. But John said no, core updates in Google Search are unrelated to Google My Business (Local search data).
Here is what John said:
As we know Google Local and Google Search both are pretty separate, they are a bit more aligned today in that some algorithms used in search can be used separately in local rankings. But either case, they are pretty separate.