Fair bet the expander plug in the steerer, where the top cap bolt screws in, has crept a bit - it's very common with carbon steerers.
Loosen the stem bolts and remove the top cap. Loosen the expander (6mm allen key) a little bit then with the key still in place give it a firm tap with a hammer. This will unseat the conical nut in the base that causes the expansion, and also ensure the plug assembly is seated properly with its top flange nice & snug on the top of the steerer. Tighten the expander quite firmly.
Install the top cap and gently tighten it a little at a time, checking frequently until you eliminate any free play. when you're happy with the cap tension, tighten the stem bolts to the correct torque setting.
Also check the rear brake cable where it feeds into the frame. Sometimes the stops can get a bit creaky, especially the cut end of the outer cable in the ferrule.
PS: I assumed this was your TCR. If it's not Di2 equipped, also check the gear cables in the upper stops. If the outers are old, the steel reinforcing tends to protrude from the PVC layers & get really creaky in the ferrules. You'll need to loosen the cables enough to at least pop them out of the stops & pull the ferrules down to check the ends. If they need trimming you'll need to unthread the cables at least far enough to trim a few mm off the outers. If the outer ends are looking rusty & scruffy just replace them.
Just ride the bloody thing and enjoy yourself!