Hi @ascorbic we seem to be hit by this issue (reported here: Gatsby v4 Builds suddenly killed, exit code 137 - #17 by slashdata) but unfortunately in our case migrating from Gatsby v2 to v4 is not at option in the short term (due to the workload involved)
Given that the issue seems to be related to the use of single core when building I was wondering if Netlify could provide the option of using multi-core in order to bypass this issue?