Venu 3 heart rate

Today I noticed something strange and wanted to ask you if it is the same for you. After climbing the stairs I looked at my watch and it said my heart rate was 107, after 5 minutes I looked in Garmin Connect and it said my max heart rate was 99. I also noticed this discrepancy in training but I didn't give importance, for example 161 on the watch shows me a maximum of 159 in the application.