Edit: For reference, this https://i.imgur.com/eKDdJlS.png is how your chainring is attached, [1.] goes on the BB spindle. [2.] gets a bolt that screws into the inside of the crankarm. But in your case, the [1.] hole may be ovalised and requires inspection. If okay, you just fit the sprocket adapter.
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It’s just the chainring that’s loose.
If it’s been like that for a while then the hole is possibly ovalized.
If it’s been fitted recently, you may be missing a spindle spacer that sits in the chainring. E.g. this https://bankruptbikeparts.co.uk/products/blank-bmx-chain-wheel-front-sprocket-adaptor-for-25t-chainring-22mm-to-19mm You’ll need to measure your spindle and inspect the chainring anyway.
Edit: For reference, this https://i.imgur.com/eKDdJlS.png is how your chainring is attached, [1.] goes on the BB spindle. [2.] gets a bolt that screws into the inside of the crankarm. But in your case, the [1.] hole may be ovalised and requires inspection. If okay, you just fit the sprocket adapter.