The new car will be powered by Ferrari once again, with Alfa Romeo continuing their partnership, but it will lack Ferrari's gearbox.
Furthermore, the prevalence of one-year contracts had resulted in a severe lack of job security, which had begun to weigh heavily on Bottas' mind.
Alfa Romeo has seen fit to rejuvenate ahead of the season, with F1 entering a new era in terms of the regulations in 2022.
Bottas was backed up by Felipe Massa at Williams before joining Mercedes to accompany Lewis Hamilton at Mercedes.
Russell has joined the 2021 Constructors' Champions to replace Valtteri Bottas, who has moved to Alfa Romeo for the 2022 season.
Four days after winning the dramatic Abu Dhabi GP, the 24-year-old got his hands on the driver's championship trophy.
The Dutchman later remarked on how it felt to go toe-to-toe with a seven-time champion during this 22-race season.
The Dutchman clocked a brilliant 1m22.109s to take his 10th pole position of the season, with Hamilton finishing second 0.371s back.
Hamilton passed Verstappen at the final corner on Lap 43 and pushed him wide at Turn 27, taking the lead and putting in the fastest laps.
Max Verstappen was fastest in the first two sectors of his final flying lap but crashed in the final corner after an unfortunate lock up.