Hiya @leftclicktwice . Pretty easy to see the difference in the build logs, which I expect explains the different behavior in the builds:
from jolly-blackwell-c29d31:
1:16:34 PM: Now using node v12.18.0 (npm v6.14.4)
from suspicious-goldstine-eb2ca5
5:42:39 PM: Now using node v10.24.1 (npm v6.14.12)
I suppose you haven’t seen or followed the advice in [Support Guide] Debugging Netlify site builds about being very explicit about setting all your versions for node, npm, etc, and you’d be well served to follow it. Sites created at different times on our service will have different defaults (based largely on what is current at the time) and we never change those defaults on all sites so the best practice is to be explicit in your configuration.