AngularJS and Angular (what you referred to as Angular 1 and 2) are completely different frameworks. It’s a branding issue, not a technical one.
Angular, from version 2 to 15 in the past 8 years, has been completely backwards compatible, and even stayed on the same paradigms. Angular code from 8 years ago looks almost the same as modern code. Which is much more stable than react’s codebase.