Tectonic and volcanic activity release CO2 into the atmosphere. They comprise a major part of Earth's carbon cycle. Over time, carbon would be depleted from the outer lithosphere without this replenishment, and one of the mechanisms by which the Earth ultimately becomes unsuitable for life is a slowing of the tectonic cycle and depletion of said carbon.
This point is addressed (briefly) in TFA:
If or when Earth’s large-scale subduction shuts off in about 3.5 billion years, kneecapping the planet’s ability to bury carbon...
See also:
"Evolution of Earth’s tectonic carbon conveyor belt" (2022)
Concealed deep beneath the oceans is a carbon conveyor belt, propelled by plate tectonics. Our understanding of its modern functioning is underpinned by direct observations, but its variability through time has been poorly quantified. Here we reconstruct oceanic plate carbon reservoirs and track the fate of subducted carbon using thermodynamic modelling....
This is somewhat speculative, and the precise nature / timing of carbon collapse may differ. But what strikes me is that the various pathways by which Earth exits its Goldilocks state are numerous and comparatively soon on a geological timescale. We're far nearer the evening of Earth's day than its morning, by multiple such measures.
