They are optional for what it’s worth. They are also landing in standard JS soon.

The proposal is stuck at stage 3. AFAIK, to proceed to stage 4, it needs two independent implementations, but Firefox [0] and Chromium [1] didn't see any progress in this area for about a year. Personally, after working with Angular for many years, that's not a language feature I am looking forward to.

[0] https://bugzilla.mozilla.org/show_bug.cgi?id=1781212

[1] https://issues.chromium.org/issues/42202709

I wouldn't hold my breath. Decorators landing in standard JS "soon" has been the claim for about a decade running.