last year I asked the same about this bug which I have concluded was a predator mite.
I found a few of them on various plants.
The big problem I have/had with these predatory mites is that they tend to hide a problem but neve deal with it completely.
Outdoors this is generally a good approach but indoors imo this can easily lead to disasters.
The problem is that if you have predatory mites you most likely have thrips that are keeping them alive.
As noted the mites tend to decrease in numbers from time to time when humidity drops. Indoors this can be a problem if the thrips then take over. It's like having a guard dog who sleeps 12 hours a day and is on guard the other 12 hours. If robbers break in every time the dog is sleeping then having a dog is pointless.
I'm not saying thrips are there but man are they resilient... mites eat the ones on the surface you would normally spot and thus dn't spot them. Months go by. Then the mites do into hybernation or something and bam the thrips are back and worse than ever (till the mites can breed and catch up again) by which point the thrips have started jumping off to 10 different pots.
So yeah not a big fan of them even if they are harmless. They do more harm than good indoors imo.
Outdoors I completely understand their purpose, they control the numbers well and thrips can never take over a plant as well with rain and wind so controlling the numbers is enough to prevent much damage.