Flaws are easy to make up with. Make them dumb, or physically weak, or addicted to something, or have a McGuffin stuffed up their ass that explodes in a time limit unless something is done with it. Those can be called flaws, but honestly speaking, they will be a pain in the ass to write. If your character flaw is just something you pulled out of the bucket to prevent your MC from looking like a Mary Sue, then you might as well just write a Mary Sue, because nothing is more infuriating than a character who can CLEARLY curb-stomp their way into a story be blindsided by some stupid flaw like "can't talk to women" or "has a phobia of the colour red".
Imagine Rey Skywalker from the nu-Star Wars trilogy being afraid of dust. I'd rather take the current Rey than that made-up version of Rey because AT LEAST the former can get shit done while the latter is the writer's poor attempt at balancing the character when all it really amounts to is filling in the blank on the other side of the scale.
You can make character flaws all you like. It's as easy as rolling a -phobia dice and see what you land on. What you should be focusing on is making a character flaw relative to your story's theme, or character goal. Is the theme of your story about letting go of the past? Then make your MC hold grudges harder than elephant glue. Is your character a rookie cop trying to unravel a conspiracy in the seedy underbelly of the justice system? Make the rookie cop a guy who's way too trusting and naive, then write your way out from there. Is it a story about greed? Then make your character, well, greedy. Is your story about finding one's true self? Then make your character a turbulent, narcissistic piece of shit who has to make amends for his own mistake.
Theme is king in a story. I've said this so many times that I've gone past being a broken record and became a literary equivalent of the CIA MKULTRA project. Pinpoint and understand the objective of your story and the relevant plot points, story beats, and the tonality that goes with it. After doing that, think of a crutch that not only elevates the theme of the story but props up the rest of said story's elements too.
For example, I'm making a story about a robot wanting to know what it's like to be human. The theme of the story is the exploration of the human condition through a third-party's lens. I'm going to establish 3 tones now: a dreaded, nihilistic tone, and a hopeless, comedic tone.
For the first tone, I'll construct a flaw that highlights the conclusion that I want to reach. The MC's flaw is that his naivety leads him to believe that human-made movies are the perfect reference for his research on the human condition. Thus, he acts out the Seven Deadly Sins in all seven arcs, highlighting the worst of human atrocities. He commits murder, rape, torture, manslaughter, theft, robbery, lies, with a heavy dose of violence throughout, all according to the action movies he sees, because it is what he believes to be human. In the end, the MC finds a kick out of it, with the kick being a feeling of comfortable repetition every time he does something reprehensible. He thus reaches that conclusion that he has understood the human condition via human sins, and continues to do so until his battery runs out or water gets into his circuit or some bullshit like that. It not only elevates the nihilistic tone but also reinforces the theme of the story.
For the second tone, we'll make that MC a clueless sod who takes things too literally. When people reference having butterflies in his stomach, he literally goes out of his way and does that, leading to some antics. When a character states that they're on cloud nine, the MC constructs an aerial apparatus capable of sending man to the stratosphere, just to experience what said character felt. It also reinforces the theme, but it presents itself in a different tone, suitable for the story told.
Don't just make a flaw because you feel like it'll make your character complete. Make parameters. Figure out what drives your story, and construct a character that'll make that drive a worthwhile experience.