sorry for taking a few days with this, I wanted to take it seriously. at the same time i'm not a professional and I don't know the specifics of your situation, so like all online mental wellness advice, take what works and leave what doesn't. <3 but based on my experience with other negative feelings spirals, some of this might be helpful:

• Do not fall into the trap of comparing your (perceived) skill level or productivity to anyone else's - it's not fair to you OR to the person you're comparing yourself to! we're all on our own creative journeys and have different creative processes, so expecting your output to be identical to anyone else's isn't realistic. you're not an AI, you're a human with unique strengths and flaws, and those both add touches to your work that makes it personal to YOU and you alone. other people can't make what you make in the same way that you make it! and so you shouldn't expect yourself to make what other people make in the same way they make it. also keep in mind that you don't know what's going on on the other side of the screen; maybe that person who's cranking out a dozen finished art pieces a week has a messy personal life and is using art as a distraction, for example. I think it's incredibly important to treat both yourself and the person you're jealous of with compassion at every step. The 'sour grapes' method of dealing with jealousy (where you want what something else has and realize that it's unattainable, so instead you internally shit-talk it in order to reassure yourself that not having it is actually Good and that the person who has the thing you want is Bad) is a natural inclination for some people, but neither healthy nor helpful in the long run, so it's good to challenge needlessly unkind thoughts (INCLUDING needlessly unkind thoughts directed toward yourself!!!) and steer yourself away from that type of coping if you find yourself gravitating toward it a lot.

• Unplug. 'Touch grass' is used pretty dismissively a lot of the time, but it's also good advice. go outside if you're able to, and if that's not in the cards try to spend some time doing an indoor hobby that's not related to fandom at all, at least a few times a week minimum. This can distract you so when you're ready to come back to fandom it will feel like less pressure and have fewer negative feelings hanging over it. I think this one might work particularly well if what's sparking your jealousy is something like follower count - disconnecting from the grind of social media might help reset your brain a bit.

• Finally, if there's someone who you just can't make yourself be rational about no matter how hard you try, who sets off your insecurities or just makes you feel bad about yourself in a way that you can't cope with at this point in time, it's always okay to unfollow, mute, or block them. temporarily or permanently. even if they didn't do anything 'wrong.' Someone can be perfectly wonderful and still bring out terrible feelings in you through no fault of their own, and deciding to curate your online hobby space in order to step away from those feelings is fine!

take care anon, I hope some of this helped or at least didn't completely waste your time orz