A profile picture is one of the most-viewed images connected to your name — it shows up next to every comment, every post, every message, dozens of times a day to the same audience. It's a small image, but it gets an unusual amount of repeated exposure, which is exactly why small details in it matter more than they seem to.
A background with a messy room, random objects, or a busy pattern doesn't necessarily look bad in isolation, but next to a colleague's or competitor's clean, deliberate-looking photo, it quietly reads as less considered. People form impressions fast, and a cluttered background is one of the easiest, cheapest things to fix before that impression forms.
A LinkedIn profile picture generally benefits from a plain, neutral background — it signals professionalism. A more casual platform can handle a bit more personality in the background. Having one photo that you use everywhere isn't necessarily wrong, but it's worth considering whether the background fits the context each platform is used in.
If you're building any kind of personal brand — as a freelancer, a small business owner, a consultant — using the same photo, or at least a visually consistent style, across every platform helps people recognize you at a glance as they move between platforms. A wildly different photo and background on each platform makes that recognition slower.
If you already have a decent photo of yourself but the background is the weak point — cluttered, oddly colored, distracting — that's fixable without retaking the photo. Swapping the background to something clean and neutral keeps the photo you already like while removing the one detail that was holding it back.
It's a small detail in the grand scheme of an online presence, but it's one of the few that gets seen constantly, by everyone, without exception — which makes it worth the two minutes it takes to get right.