Thanks a lot for your answer @hrishikesh but my feeling is that something changed on Netlify during these last days which triggered this error. As I mentioned in my original comment, we’re using 2.23.3 (a rather old version, I know) and we didn’t perform any change in our code base for weeks, so I can’t find any explanation other than something changing in your build environment.
Thank you for the reference to that issue, but unfortunately in our case upgrading to v4 is something we can’t afford to do right now, given that such upgrade would take days to be done.
So if the issue seems to be due to using single-core for building, I’m wondering if there is any way to set this in Netlify (perhaps upgrading plan?) in order for this bug not to happen and to buy some time until we do the gatsby update, etc. Otherwise I’m afraid that our only option would be migrating to AWS (I just set CodePipeline and the project built as expected) at the expense of having to also migrate our forms and functions functionality which we were using through Netlify.
Thank you in advance.