Does tf2 rely on current time or only on message header time?

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We recorded some rosbags and now we want to play them for simulation. But Ros2 Foxy doesn't have a feature like Ros1's use_sim_time and we can't switch to Galactic. In order to use the rosbags we need to know whether our code relies only on time provided in message headers (as recorded in the rosbag), or also the current time. Since we're using tf2 as well, I'd like to know whether tf2 relies only on time provided in message headers, or also the current time. Anyone knows?