"lead author Erik Asphaug" My observation, a busy writer and NASA ADS Abstract service shows this
The collision chains model for Earth and Venus is reported at this site too. Earth and Venus grew up as rambunctious planets,
https://phys.org/news/2021-09-earth-venus-grew-rambunctious-planets.html
"What doesn't stick comes around: Using machine learning and simulations of giant impacts, researchers at the Lunar and Planetary Laboratory found that the planets residing in the inner solar systems were likely born from repeated hit-and-run collisions, challenging conventional models of planet formation. Planet formation—the process by which neat, round, distinct planets form from a roiling, swirling cloud of rugged asteroids and mini planets—was likely even messier and more complicated than most scientists would care to admit, according to new research led by researchers at the University of Arizona Lunar and Planetary Laboratory."
Indeed, a very messy work to make the solar system now using the solar nebula and spinning, protoplanetary disk said to create all we see today in the ecliptic
Concerning the Moon forming impacts now, much is going on in the simulations. My observation. It looks like this model needs two giant impacts now to make the Moon, not just one impact using Theia as the impactor. There remains the question for me as to how much gas and dust mass is used in the model for the region between 0.7 au out to 1.0 au as well. Erik Asphaug is published on the multiple giant impacts model to make the Moon. Moon Formation in Three Acts,
https://ui.adsabs.harvard.edu/abs/2020EPSC...14..485A/abstract, September 2020. "Overview. Terrestrial planets grew in a complex series of late stage giant impacts, and Moon-formation was among last to occur around Earth. But was it a singular event? Here we propose it was three or more episodes involving two bodies and the Sun, an almost-merger followed by an interlude, followed by a merger...To address the major deficiencies of the standard model while preserving its major strengths, we have developed a theoretical basis for a collision chain origin of the Moon. We show it to be a common pathway of planet formation, slowing the random velocities until merger is probable. There are innumerable pathways so it is premature to hone in on one scenario. A scenario meriting further research is an ~0.2 MEarth planet that become a mantle-stripped Theia, that then returns thousands to millions of years later for a merger on a strongly unaligned impact axis...To represent all possible collisions, we clone each SPH outcome into 1000 random orientations and evolve each clone, including the other major planets, until they have another collision with a planet, or for 50 Myr when most giant impact chains are finished."
There is plenty going on here with various impacts and time scales used. I still would like to see a proto-earth rock and Theia rock, perhaps from the 0.2 earth mass model on display. However, this is likely asking too much of the model at present