TypeScript Version: 3.8.3 and next (3.7.x works as expected)

Search Terms: unique symbol class expression

Code

// tsc --target esnext --strict
const s = Symbol();

class A {
    [s]: number;
    constructor() {
        this[s] = 42;
    }
}

const B = class {
    [s]: number;
    constructor() {
        this[s] = 42;
    }
}

const C = true && class {
    [s]: number;
    constructor() {
        this[s] = 42;
    }
}

Expected behavior:
No errors
Actual behavior:
error TS7053: Element implicitly has an 'any' type because expression of type 'unique symbol' can't be used to index type 'B'.
Property '[s]' does not exist on type 'B'.

13 this[s] = 42;
Playground Link

Related Issues: Did not find any

Only the B example doesn't work. It doesn't matter if the class is named or not. Returning the class from a IIFE also works without errors.