hi anon! i think the best way to deal with this is to view it as a growth opportunity. every time i read something that gives me that God I Wish I Could Write Like That feeling, i always try and figure out what specifically i admire about it and how i can apply it to my own writing--like is it the dialogue or the humour or the word choice or the imagery or some interesting aspect of figurative language or structure or... etc. by shifting the focus to myself and how i can improve, the issue of comparison/competition just never arises. so i guess my advice boils down to Just Be Really Self Absorbed but i do mean that so sincerely! it's all about YOU. if you see something you like, try it yourself (obviously i don't mean lifting phrases word for word, but like for example if i've read something that's used language in a highly experimental way i might try and write in a more experimental style myself to see how it works). everything is only a chance to improve your craft.

i also think it helps to look at fic as a community experience rather than a competition--it's not a zero sum game, there's plenty of audience for everyone. highly recommend doing things like sprints / brainstorming sessions / beta work with a few writer friends! it helps with actual productivity and with reframing writing as a collaborative thing (even if just in the sense that fic exists in dialogue with a broader fandom) rather than a you-vs-the-world thing.

wishing you the best in your writing endeavours!! i know that insecurity/competitiveness is a difficult feeling to manage but in the end we are really our own worst critics and i find that taking practical steps to harness that feeling into helping you bridge the gap between your level and where you want to be, and to make everything about yourself, is the most effective way to handle it <3