Not now, but over the first year of lockdown DD (then 7) went from a healthy weight to distinctly chubby. Definite rounded tummy, thighs were much larger, ribs no longer visible or very easy to feel. It was a combination of being stuck inside/lack of running around with her friends at school, & comfort eating due to boredom, sadness at being stuck at home, etc.
I started insisting she have at least 2 proper servings of non starchy veg with every meal (e.g. carrot sticks & cucumber with a sandwich, various cooked veg if it was something hot). Lean-ish protein, less processed meats etc. No crisps, puddings, or other "treat" food unless she'd eaten all her proper food first. Sweets, crisps etc are not proper food. Snacks were fruit or sometimes a piece of cheese, but mostly we're a non snacking family so she rarely asks. Switched to mostly toast with protein, porridge etc rather than processed breakfast cereals several days a week. We don't really drink squash, fizzy drinks etc anyway so I didn't need to change that. I don't do low fat options e.g. margarine, mayonnaise, I just made sure the fats she had were as healthy as possible, less refined, etc.
We also started going for walks (because lockdown, boredom, etc). She also got interested in doing some of the more fun exercise games on the Switch (for rainy days etc). Between that & the dietary changes, she slowly started to slim out, & just didn't put any more weight on for about another year, but did get a hell of a lot taller - over 6 inches in a year. I was worried for a while about the massive growth spurt being an indicator of early puberty but that didn't happen. She's back to her usual centile for her height now, has been for a while.
Generally we let her eat more when she's hungry, & don't push her when she's not. But we do usually stick to the above now, except that we let her have cereals some mornings (still has porridge/toast whe she wants). And now she's older she occasionally gets a can of fizzy pop.