You fix one pattern: domain code is asserting or probing an unknown shape instead of parsing it once at the boundary.

Fix Shape

Prefer Schema.decodeUnknownEffect(MySchema)(value) for untrusted input.
Prefer Schema.decodeUnknownEffect(Schema.fromJsonString(MySchema))(text) or Schema.decodeUnknownOption(Schema.parseJson())(text) for JSON strings.
Keep domain code typed after the decode; do not keep unknown and probe it repeatedly.
Replace JSON.parse, value as string, as unknown as X, as Record<string, unknown>, inline object assertions, "field" in value, and Reflect.get with a schema, typed adapter, or named guard.
A named guard is acceptable only when parsing is not the right abstraction and the guard has a precise return type.

Good

const ParsedConfig = Schema.Struct({
  endpoint: Schema.String,
});