How to parse multiline json in Promtail - json

Question

I am using log4js to log data to a file in my app. I want to display some of this data in my Grafana dashboard and for that I am using Promtail to read logs from the file, pre-process it and send it to Loki. In Loki, I want to filter the data based on the parsed values.
Here is an example of my logs:
[2023-02-12T04:01:23.587] [DEBUG] default - {
"message_id": 123,
"from": {
"id": 123,
"is_bot": false,
"first_name": "XXX",
"last_name": "XXXXX",
"username": "XXXXX",
"is_premium": true
},
"chat": {
"id": 123,
"title": "XXXXX",
"username": "XXXXX",
"type": "supergroup"
},
"date": 123,
"message_thread_id": 123,
"text": "XXX XXXXX XXXXX"
}
Here is my current Promtail configuration:
server:
http_listen_port: 80
grpc_listen_port: 9095
log_level: debug
positions:
filename: /tmp/positions.yaml
clients:
- url: http://192.168.1.64:3100/loki/api/v1/push
scrape_configs:
- job_name: patriotbot
pipeline_stages:
- multiline:
firstline: \[\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{3}\]
- regex:
expression: '^\[.*\]\s\w*\s-\s(\{.*\})'
name: log_entry
- json:
source: log_entry
name: only_json
expressions:
from_id: 'from.id'
is_bot: 'from.is_bot'
first_name: 'from.first_name'
last_name: 'from.last_name'
username: 'from.username'
chat_id: 'chat.id'
chat_title: 'chat.title'
chat_type: 'chat.type'
- output:
source: only_json
static_configs:
- targets:
- localhost
labels:
job: patriot
type: all
__path__: /logs/all.log
I have two issues with my current configuration:
My logs are saved as multiple lines, making them difficult to parse. I have attempted to fix this issue with the multiline stage, but which is displayed properly in Loki, though maybe it won't work for following parsing.
The timestamp and metadata in front of the JSON object is preventing it from being parsed properly. Should I get rid it before sending it to the pipe and parse?
So can somebody suggest changes to my configuration that would allow me to properly parse these multiline logs and extract the relevant data?