Apple has started rolling out iTunes Match with audio fingerprint to all Apple Music subscribers. This will replace the current, less-accurate version of song matching for Apple Music that relied on metadata.
This is, in fact, the same version of iTunes Match that iTunes users could pay for as a separate subscription since Apple began offering it years ago. I am one of those users. However, all subscribers to Apple Music will get the new version of iTunes Match at no extra cost.
If a song had previously been incorrectly matched by Apple Music, it will be replaced by the correct version once the new iTunes Match with audio fingerprint rolls out. Importantly, it will not replace songs that have been downloaded onto your device.
Apple is taking a steady approach to the rollout of the new iTunes Match for Apple Music, moving over 1-2% of its users every day. The rollout will happen automatically, so you won't need to do anything.