The seat count can't exceed 150 total.
I was expecting C16Y132 or C12Y138

Maybe they are blocking some economy class seats in case of equipment swap? Hence C12Y134, but unlikely. Could be a glitch.

I don't think it's going to be the glowing hearted cabin, it's likely part of the dream cabin refit.

I think AC will try keeping the 150 seat capacity to avoid having a 4th FA onboard. Spaceflex lav may not be needed.