i see this all too often... person posts music (or artwork/etc) with a built-in caveat of "i know this sucks but," or "made a little thing i know it's not much but," or "the [blank] needs work and the [blank2] is whatever and the . . ." and this is such a bad habit to get yourself into. you are literally priming the listener/viewer to see flaws in your work before they even engage with it. you have altered their first impression, or worse, prevented a prospective person from even interacting with it in the first place. if i sense you're not taking pride in your work or taking it seriously or whatever, why should i? or as somebody else i know has put it, "if someone tells me their music sucks i believe them π€·".
like, ok, ok, a ton of us struggle with not feeling good about our output (or some aspect of it), and for all sorts of reasons! everybody's trying to learn and get better, everybody's at a different point along their arc of thingmaking-skill, we are constantly comparing ourselves to others and seeing their work all around us, we each have our own goals to try and meet. it's normal to possess some vulnerability in this realm. confidence isn't built overnight and neither is one's craft. but what you shouldn't be doing is projecting that outward while you share your work. you can simply not say any of those belittling things in this process, and maybe someone listens to your thing and concludes on their own terms, for whatever reason, that it's not good! too bad for them! but maybe also they listen and they think oh wow that was pretty cool, whereas if you'd prefaced your post with "idk how to not suck at music lol" they might've instead found it amateur or simply not clicked it to begin with. how you present yourself matters!!! even outside of a professional context.
there are more productive ways of phrasing or channeling those sorts of feelings; for instance if you do really think the mixing of your song is scuffed, you could voice this as a feedback request: "feeling unsure about the [blank and/or blank2] in the mix here, how does it sound to you? any suggestions?" and now the person is primed again but in a way where they're being asked to consider it deliberately and you might be given ideas to try - a tangible step forward for you. maybe you don't want feedback; you could just say you're workshopping the mix! or just don't bring it up at all and see what people say or react to! post your thing with pride. not everything is gonna be your best work, not even close, so you don't have to pivot hard in the other direction and act like it is; but at the same time you have no idea what's going to resonate with people - somebody is gonna get struck by your lightning at the most unexpected time. that's beautiful, so don't inhibit that process!
last thing - i called it a bad habit at the beginning and i want to make an important point there. it is a habit. the more you get used to acting self-deprecating the more you'll continue to do it, the more you'll internalize those feelings. it's a habit you can break with some effort! build the better habit of presenting your work somewhere on the line between neutrally and positively. it gets easier every time! and you will add a few bricks to your confidence wall in the process.