How can i hide fcm firebase api key? when i use react-native

Question

I am using react-native and mysql.

firebase is only used for push notifications.

In the backend, i can hide the api key by using .env, but the problem is that the firebase api key is used in the front.

How can I hide the FIREBASE_API_KEY in this case?

Also, do I need to hide the firebase api?

this is my code

        const TextInput = ({hideTodoInput}) => {


          async function sendmessage() {
            const message = {
              to: fcmusertoken,
              notification: {
                title: `${me?.nickname}님이 댓글을 남기셨습니다`,
                body: commentText,
                sound: 'default',
              },
              priority: 'high',
            };
        
            const FIREBASE_API_KEY = 'firebase api key'   //how can i hide this firebase api key?

            let headers = new Headers({
              'Content-Type': 'application/json',
              Authorization: 'key=' + FIREBASE_API_KEY,
            });

            try {
              let response = await fetch('https://fcm.googleapis.com/fcm/send', {
                method: 'POST',
                headers,
                body: JSON.stringify(message),
              });
              response = await response.json();
            } catch (error) {

            }
          }

          return (
            <Input
              autoFocus={true}
              autoCapitalize="none"
              autoCorrect={false}
              placeholder="댓글달기"
              returnKeyType="done"
              value={commentText}
              onChange={onChangeCommentText}
              onSubmitEditing={() => {
                onSubmitComment();
                hideTodoInput();
              }}
            />
          );
        };
        export default TextInput;