According to the lore, by the beginning of the Mandalorian Wars, Revan was already a Grand Master... it's still unclear whether he was already a Dark Lord or just beginning his path to the dark side... but what is certain is that Malak was a Jedi before Revan took him under his wing...
Perhaps the events of the Mandalorian Wars, the battle on Malachor 5, caused Revan's fall to the dark side... One thing was absolutely clear... that Revan appeared in those turbulent times as a call to the Jedi of the galaxy to confront this threat. But at the same time, this was a war not only against the Mandalorian forces... something was hidden behind these wars... Revan was searching for the source... the source that prompted the Mandalorians to begin their crusade against the Republic... In the story of Mandalore from the second part, it was known that previously Dark Lords... Exar Kun... possibly Freedon Nadd were behind the actions of the Mandalorians... now, someone else could be playing the same puppet master role... someone unknown...
That is why the Civil War broke out, the end of which is described in KOTOR... Revan was creating an army... an army to finally defeat those who were behind the Mandalorian Wars...

Maybe this is just my opinion, but what could be learned in KOTOR 2 led me to this conclusion...