Hi @Jmn, that is very strange that it dropped so rapidly. Let us know how you go with a full charge.
If the issue continues, I suggest sending an error report via the Samsung Members app for this to be investigated. Error reports are sent to our team to identify any deviations in your device performance, once analysed, our team will get back to you with a response to advise further.
To send an error report:
Samsung Members > Get help > Error reports > Battery > describe issue and frequency > Tick ‘send system log data’ > Send in top right.