2042 is hosted on Amazon servers. FlexMatch is a matchmaking service Amazon offers to game developers. DICE hasn't said if they're using FlexMatch, but I'm pretty sure they're using it.
Key FlexMatch features
The following features are available with all FlexMatch scenarios, whether you use FlexMatch as a standalone service or with GameLift game hosting.
Customizable player matching. Design and build matchmakers to suit all of the game modes that you offer your players. Build a set of custom rules to evaluate key player attributes (such as skill level or role) and geographic latency data to form great player matches for your game.
Latency-based matching. Provide player latency data and create match rules that require players in a match to have similar response times. This feature is useful when your player matchmaking pools span multiple geographic regions.
Support for match sizes up to 200 players. Create matches of up to 40 players using match rules that are customized for your game. Create matches of up to 200 players using a matching process that uses a streamlined custom matching process to keep player wait times manageable.
Player acceptance. Require players to opt in to a proposed match before finalizing the match and starting a game session. Use this feature to initiate your custom acceptance workflow and report player responses to FlexMatch before placing a new game session for the match. If not all players accept a match, the proposed match fails and players who did accept automatically return to the matchmaking pool.
Player parties support. Generate matches for groups of players who want to play together on the same team. Use FlexMatch to find additional players to fill out the match as needed.
Expandable matching rules. Gradually relax the match requirements after a certain amount of time has passed without finding a successful match. Rule expansion lets you decide where and when to relax the initial match rules, so that players can get into playable games more quickly.
Match backfill. Fill the empty player slots in an existing game session with well-matched new players. Customize when and how to request new players, and use the same custom match rules to find additional players.
https://docs.aws.amazon.com/gamelift/latest/flexmatchguide/match-intro.html