If you have an alloy seat post in your carbon frame, I suggest you go out to the shed or glass cabinet and see if you can still move it. If you can then get it out ASAP and do 1 of 2 things:
1 – Grease the seat post with carbon gripper grease. Keep refreshing it every season. Look at pic 3 if you want reminding.
2 – Get a carbon seat post. It can still jam but not nearly as badly.
Alloy and carbon are reluctant bedfellows. Any wet or winter grime seems to irritate that partnership into an eternal head lock….. It’s not pretty to remove! Sometimes that could be the end of your bike…… Remember that to ‘grease and forget’ is a mistake.