Yes, but it depends on the speed you are going
> If regenerative braking is aggressively slowing Model Y (such as when your foot is completely off the accelerator pedal at highway speeds), the brake lights turn on to alert others that you are slowing down.
https://www.greencarfuture.com/electric/does-regen-braking-t...
Seems pretty obvious, the idea is that engine braking would also cause your car to slow down without lighting up the brake lights so any kind of slowdown at that level would not normally engage the brake lights. But as soon as you slow down more than that the lights will come on, making its behavior pretty close to what you'd expect from a regular car with and ICE lacking regenerative braking.
Or would you suggest that a normal car should engage it's brake lights when you let go of the accelerator and engine brake? (I can see a case for that.)
In comparison, my 2015 Leaf doesn't illuminate the brake lights during regen but it's regen is significantly less than my Model 3.
For Tesla Model Y:
> If regenerative braking is aggressively slowing Model Y (such as when your foot is completely off the accelerator pedal at highway speeds), the brake lights turn on to alert others that you are slowing down.
Source: Model Y manual: https://www.tesla.com/ownersmanual/modely/is_is/GUID-3DFFB07...
1: https://www.greencarfuture.com/electric/does-regen-braking-t...