Is there a gate limit at Faringdon to control overcrowding? If too many passengers are on the platforms, the gate barriers being closed to down to prevent entry to the statioon until sufficient passengers have departed
I imagine this will be an assessment made by the local station control room (managed by London Underground). However there is general guidance out there on what is seen to be "heavy" crowding which is normally when you can only see heads on a CCTV camera and no space between people.
A key difference is that at most underground stations people board the next train that comes, whereas in the Thameslink core there will be people standing for their train and not moving for the one or two trains that don't go to their destination.
At a station like St Pancras is isn't really an issue as the platforms are big, but parts of Farringdon are a lot more problematic.
There are of course a fair few tube stations with different train services that will have a similar issue and presumably the same risks.
This will definitely be an issue, especially as people can line up the door locations after the next service has arrived. The same thing happens on the Elizabeth Line, only the platforms are evidently much wider.