In one of the updates, Valve returned the ability to conveniently monitor ping, server and client operation, and the FPS counter, instead of the old inconvenient option (cl_showfps 1).

The new feature has become available both in the game settings menu itself and through the console. In order to enable telemetry (this is the name of the added function) through the console, just enter one command into it: cl_hud_telemetry_serverrecvmargin_graph_show 1

To turn off telemetry through the same console, change the value of 1 to 0: cl_hud_telemetry_serverrecvmargin_graph_show 0

Go to game settings → Game → and look for the Telemetry item
In order for telemetry to be visible constantly, and not only during network and client failures, you need to set the parameters Always in all three available items.