Yep, where I live (rent) a 3m wave would fill my house with 1m of water. Even if it was one quick wave, that washed over without staying long enough to completely flood the inside of my house, I'd probably at least have to deal with a bunch of water damage.

My crude understanding and associated mental imagery is that tsunami waves are more like tide than "usual" waves: your typical 3m wave is mostly "surface-ish" in comparison, while 3m tsunami has both greater wavelength and "depth", which is what makes the "usual" wave break quickly when it reaches shore, whereas tsunami waves continue pushing real hard for real long because of all the length * undersurface water you don't see.

Gently shaking a glass of water sideways or blowing upon it won't make much water spill out, but jolt it vertically and most of it goes out real quick.

This is all probably very incorrect physics but it helps drive my intuitive understanding that 3m wave and 3m tsunami are quite different, the former being scary but the latter being muuuuch scarier.

Our local offshore break that we grew up with as kids was, and still is, a total monster in storm (a long way back and out to sea) conditions:

https://www.youtube.com/watch?v=xjHaFOGBPzk&t=138s

https://www.surfertoday.com/surfing/the-right-the-monster-we...

It's a little bigger than 3m at the face and is a "slab" .. not a thin wave but one backed by a mass of water.

Somewhere in that video you might see a triple lip .. three curling breaks, one within another and another again.

I know 3 m waves are powerful, I was within them.

But they are normal on most coast and that they are bad on a flat beach I can imagine. But Taiwan is quite steep, so aside from some damaged boathouses, I cannot see the big danger (compared to the consequences of the earth quake). But apparently no Tsunami came.