None, in the months (sometimes years) it spends switched off (off, not standby) between print jobs. It's a quarter of a century old and I can still get replacement cartridges when I need them.

Extremely little? High quality inkjets may make sense for corporate or industrial uses, but the majority of home/consumer use cases probably print very infrequently these days. In that scenario inkjet is pretty bad because the ink dries out between uses - there is a reason it's such a common trope that inkjets never work right when you need them.

I switched to laser because I only print like maybe once a month on average (but when I need it, I need it). I'm not the slightest bit worried about the delta energy usage between my laser printer or the inkjet, and I'm sure the inkjet came out worse given the number of cartridges I had to throw away or paper I wasted printing diagnostics.

Are you counting the energy used for print head cleaning, and to manufacture all the wasted ink?