yeah man but what the fuck are those? I've found the same thing on the bottoms of my leaves as well and I'm freaking out loll.
then, I've pretty much read every article and thread on the internet about it and what you see in the picture are just glandular trichomes found both above and below the leaf. I am unfortunately hyper paranoid and already a year ago when I checked well I noticed these trichomes but due to negligence I let it go also because there was not even a sign of insects or pests and the plants were more than fine! this year I got paranoid again because I moved to a new house and even though I disinfected everything I was afraid that some mites or anything else might lurk somewhere and I started inspecting them every day noticing again these trichomes and I went into alarm..
Unfortunately I had other problems due to a late transplant and it started showing signs that something was wrong and I did 1+1 and pinned it down that it was either mites (russet or broad) or thrips (I've dealt with them in the past and some leaves raised suspicions) , I sprayed micronized sulfur and spinosad alternating once a week and at the moment it's been a month since the thread and I can tell you they are looking nice and I never actually noticed any pests.
The only thing I can recommend if you don't see any pests is to start having a good IPM and a lot of hygiene of the growing environment so that you are always one step ahead instead of being unprepared in a situation where you then have to spend time identifying, finding the treatment, buying it (with wait times if you have to buy the product online) and applying it and you will still end up with a lower yield and quality than a plant that starts off smoothly. And above all, it saves you from fighting every cycle because anyway if you encourage their development or if you lose control of the infestation, it is difficult to eradicate them and you risk that out of "laziness" all your next crops will be affected.
Sorry for the scroll but I felt like you groping in the dark without a good answer about it and I feel like recommending this so that you baypass the problem regardless