Pipewiresrc does not respect the framerate cap when running inside flatpak

Application Development
1

As title.
pipewiresrc does not respect the framerate cap when running inside flatpak

I have tried pretty everything but it does not work.

this pipeline

pipewiresrc fd={1} path={2} 
keepalive-time=PIPEWIRE_KEEPALIVE min-buffers=2 
! videorate drop-only=true 
! video/x-raw,framerate=60/1 
! videoscale 
! videoconvert

produces random frames below 60FPS when running native and when running sandboxed on flatpak.

pipewiresrc fd={1} path={2} 
keepalive-time=PIPEWIRE_KEEPALIVE min-buffers=2 do-timestamp=true 
! videoconvert 
! videorate 
! video/x-raw,framerate=60/1  
! videorate 
! video/x-raw,framerate=60/1  
! videoscale 
! videoconvert

this one produces perfect 60 FPS when running native and on snap sandbox,
but it produces a whopping 300FPS when running sanboxed in flatpak.

is there a way to make it work in pipewiresrc under flatpak?