Can you please check the phone's settings that fast charging is still activated.
Also are you able to try another Samsung charger cord and charging plug as a process of elimination.
Look inside the charging port with a torch to check there isn't a built up of debris.
To add a Samsung Experience Store or Samsung Service Centre can take a look too @gemini30
I wish you all the best with this situation.
Daily Driver > Samsung Galaxy s²³ Ultra 512Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "