Random in the sense that there are 36 teams and you can only draw X teams and Y teams from certain pots, yea.
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How will draws be made?
At the start of the season, the 36 participants will be divided into four pots of nine. Pot 1 will include the reigning champions as well as the eight clubs with the best coefficients. Pots 2, 3 and 4 will be ordered on club coefficients.
Each team will be drawn to play two teams from each pot, including their own. That means fans will be able to watch the best teams play each other much earlier than before as each team from Pot 1 will play two other teams from Pot 1 in the group stage. Clubs from the same country will generally be kept apart in the group stage. However, associations with four or more teams competing in the Champions League could play one match against a club from the same league. So fans could see two Premier League giants in action against each other in the group stage.
There will be only one draw for the round of 16 onwards, with teams being seeded based on their position in the group stage.
https://www.express.co.uk/sport/football/1814353/Champions-League-rule-changes-explained