Is the mental model switches between classes, HOC's, and effects really that taxing? Rewriting your code to match the current framework flavor is really less exhausting?

One time work to get knowledge outside your head vs mental notes for context switching while you code? For some people/projects, the first one would be much easier.

Personally I don't find hooks vs. classes much of a context switch. The mental model for the component lifecycle is more or less the same, it's mostly just a different surface syntax (there are a few extra rules for hooks like not putting them in conditionals, but you'd have those in a pure-hooks setup too).

If you understand each approach well enough they aren't context switches at all - they're just different tools for solving a similar problem. If anything, understanding each of them gives you a better understanding of the approach your team has converged on.