Watch thought I was in bed while watch was actually on the charging station

My apple watch 9 has been waking me up with alerts even during the sleep mode. Last night I left it on the charging station all night. This morning it showed me being in bed from 8:30 to 6:01 although it was on the charging station from 8:30pm until 7:40am and the sleep mode was set from 11 to 7.

What's going on? If it can't tell the difference between being on my wrist and the charging station how can I believe any other data?!