I feel like I'm (34m) being unfairly attacked at work

So I'm in my mid 30's and work at a fast food restaurant... now i've been through lots of trauma and wasn't emotionally capable to work for many months before i began working here in april of last year..

when i began, i was very slow and it took me a while to learn things... long story short, a few months later i began progressing a bit, and they moved me to grill which is a tough position but i did well...

around the time i began working here, a then 18 year old began working here... she's 19 now and is basically the assistant manager... we've always gotten along well, but like the GM, i've felt like they both and unfairly strict towards me in ways they aren't with other people...

i've heard this from two other coworker as well who also both work on grill, and they said that they make the same mistakes i do but never got called out for it...

i figured that maybe it was because i've been here a lot longer, am older than these 20 year old guys, so maybe they expect more out of me and thus are stricter towards me...

today was a day where i felt very unfairly treated...

so when i'm on grill i'm obviously cooking chicken, and other things like beans and rice that do not contain meat...

i began cooking my chicken and set the timer, then took my gloves off and grabbed the thermometer to check the temp of the beans on the stovetop next to the grill cooking the chicken...

this 19 year old assistant manager told me that it's "cross contamination" to do this because oftentimes there is chicken juice on my wrist and it could go into the pot of beans... it's not liquid dripping off your wrists, more like a dry bloodstain.

usually when i grab the raw chicken out of the bag, some juice will get on your wrists... not always... and i have longsleeve shirts so it dries up the juice, and there's really no risk for anything to contaminate the beans...

this felt excessive, but i went along with it even though i've never heard her call out anyone else on this before... so again i'm feeling unfairly treated like i have for months with these same kinds of things only i hear criticisms for...

a few hours later, it got twice as worse and i'm just in shock many hours later as i write this...

so, it's the end of my shift and i'm cooking my last chicken for the day... i cook it, and place it in a pan where i will cut it in a few minutes...

i take my gloves off, my hands are clean and there's no chicken liquid residue on my wrists since i've been washing my hands like 30 times today literally...

and so i grab some dirty dishes, walk to the back by the dishwasher and do a couple of my last dishes, and then i go back to put some new gloves on and cut my chicken, and when i'm done i take my gloves off and am about to head out for the day.

this assistant manager wrote me up for a Final Warning due to the above paragraph, which she said was "cross contamination"...

mind you, all day long after she called me out the first time, i've been washing my hands right after i cook chicken, before working with any other food like beans and rice etc...

this situation at the end of my shift involved me cooking chicken, and in her words i was cross contaminating the "deep pans" and anything else i touched... which doesn't make sense because they went into the dishwasher and my hands and wrists were clean.

so she's saying that because i didn't immeditately wash my hands after cooking the chicken, that i'm cross contaminating anything i touch such as a couple pans that i took back to do dishes with...

again, my hands were spotless with no chicken residue or anything... that's what gloves are for, and you don't always get chicken juice on your wrists when grabbing the raw chicken out of the bag... and i had no other food to cook after the chicken.

i've never seen her be this strict with anyone else, this very overly strict behavior... other coworkers have said that they never get the kind of criticisms i get even when they do the same things i do...

and to make the unfairness worse, for weeks i've noticed thermometers that we use to temp everything have what looks like meat on it from the night before, and that's being used to temp the beans and everything else...

so that's very seriously cross contamination and yet the manager doesn't write anyone up for that, but i got written up for this ridiculous stretch of "cross contamination" when it really wasn't because my hands were clean after cooking my last chicken for the day..

she recently got promoted to assistant GM and now she's able to give out write-ups... her and i get along well and i've told her how much i appreciate her... she's kind and easy going most days... but things like this make me feel taken advantage of.

tl;dr i feel like i'm being gaslit and manipulated, and unfairly treated... who's at fault here?