yeah if you have moisture you must turn the phone off immediately then you need to clean it with a cloth and put it in a bag of rice in a possibly dry environment. DO NOT shake it to try to get water out or use the hairdryer cause you will get the opposite effect.
TOP TIP: Instead of uncooked rice, try using Kitty Litter, unused. Much more absorbent. 😁
The moisture symbol should dissappear on its own. The issue is probably moisture detection on the ports. Gently dry them with a ear cleaning stick. The ones with cotton wool on the end.
If it continues @Emma39 then a Samsung Experience Store or Samsung Service Centre can take a look.
Please be aware water damage isn't covered under the Samsung warranty.
I wish you all the best with this.
Current Phone > Samsung Z Fold³ 5G.