What the hell

Is this
on my plants

Please

I tried looking at pictures of scale and pests and stuff but don’t know exactly what this is and don’t want to use the wrong treatment. It’s like gouged out spots on them but they seem mostly healthy otherwise so I’m not sure what’s happening. I had a monstera that died dramatically so I’m wondering if it’s related to this too.

If anyone has any advice I would appreciate it (and you for taking the time to help), thank you!

——-
-Watering
Orchids & cactus: when the soil is totally dry
Fig & begonia: when the top 2-3” are dry
Sea onion: idfk it’s dormant (or dead?) so not much

-Light
They all have plant lights for ~9 hours a day. The windows are west facing and don’t get much light because of an awning.