In my experience w/ Processing’s major version transitioning is to stick w/ latest previous major version for more than 1 or more years!
IMO, Processing is too eager to present new major versions as stable, while it still has beta and even alpha issues.
It has been true from Processing 1.x.x to 2.x.x, and to 3.x.x; and now to 4.x.x.
BtW, I’m still using latest legacy 3.5.4 version. Here’s a link to major stable version releases: