Video bitrate limit at ~1500kbps

I have install jitsi on my raspberry pi4, everything work smoothly. In my case, i need video transmit at 4500-6000kbps. My network can handle this. about 6month ago, everythings still ok but now jitsi stuck under 1500kbps.
I tested in many case and find out that I could archive that bitrate when i try to open new session and join to the meeting. (I disabled p2p and always keep another 3 session joined the meeting when I close and open new web tab)
I try to install older version of jitsi but problem still there.
Anyone facing this problem?
sorry for my bad english.

If you want higher than the default bitrates you’ll need to edit the config: jitsi-meet/config.js at 8127ea247925c25d53532edf0cb10f46a5011d50 · jitsi/jitsi-meet · GitHub

thanks for your reply
I edited it already. As I mention above, I got the higher bitrate by create new session and join the meeting with a litte luck. that mean I don’t know actually how can I get 6mbps. just open new chrome tab, join, and wish the best :)) I think this is the webrtc problem but can’t prove it.