Rocket Chat notifications Could not send notification id: \"undefined\", Error: Cannot read property 'send' of undefined

I have setup self hosted rocket chat server on my debian machine using snap package. Using websocket and some external APIs of rocket chat i have setup a custom flutter app. Everythings works fine except notifications.

For notification i have setup configuration where certificate and keys are required under Settings->Push copied from firebase console

On app, each time i login, FCM token is send to rocket chat server agains user using Post push token - Rocket.Chat Developer
I want that if mobile app is closed i should receive a notification but in logs i see this on new message send from admin to user

{"level":20,"time":"2023-07-06T07:10:30.681Z","pid":66241,"hostname":"chat","name":"Push","msg":"send to token {\"apn\":\"fcaHkHHOD0xSvOEb6hn2tO:APA91bHRxj_6wt3yNBb58t4Qy8GjGuH7xi7yz_pEQwKgre3oYTMzNyttrb33xvyVoCRFIKwRhisKUAivSJfJW-UUdLMjRLOlX4nUXgcIt2lb1JpxDRMQVAEH2rOSJqndrvVW06vcUmol\"}"} 
{"level":20,"time":"2023-07-06T07:10:30.681Z","pid":66241,"hostname":"chat","name":"Push","msg":"send to token {\"apn\":\"fcaHkHHOD0xSvOEb6hn2tO:APA91bHRxj_6wt3yNBb58t4Qy8GjGuH7xi7yz_pEQwKgre3oYTMzNyttrb33xvyVoCRFIKwRhisKUAivSJfJW-UUdLMjRLOlX4nUXgcIt2lb1JpxDRMQVAEH2rOSJqndrvVW06vcUmol\"}"} 
{"level":20,"time":"2023-07-06T07:10:30.682Z","pid":66241,"hostname":"chat","name":"Push","msg":"Could not send notification id: \"undefined\", Error: Cannot read property 'send' of undefined"}

It always look for an old apn token instead i am sending gcm token on POST method agains the user.

I am really confused what am i messing to acheive this goal. Any help will really be appriciated.

Server Setup Information

Version: 6.2.8
Apps Engine Version: 1.39.1
Node Version: v14.21.2
Database Migration:294 (July 5, 2023 2:25 PM)
MongoDB: 5.0.15 / wiredTiger (oplog Enabled)
Commit Details
HEAD: (27753d300)
Branch: HEAD

can provide more details if needed.