Q re: strength trainer and am I doing something wrong

I’m new to whoop (2 weeks in) and I’m just a bit confused with some of the metrics, so hoping the brain trust here can help. I did an upper body strength session this morning, approx 30 min total, low reps heavy weight - 1min rest between reps/sets, but strength trainer is telling me it was mostly cardiovascular load. I am confused??? Am I training wrong? Not sure if relevant: F53, not a beginner, 3x strength session p/w + other activities,aim is muscle build/retention.

I’m new to whoop (2 weeks in) and I’m just a bit confused with some of the metrics, so hoping the brain trust here can help. I did an upper body strength session this morning, approx 30 min total, low reps heavy weight - 1min rest between reps/sets, but strength trainer is telling me it was mostly cardiovascular load. I am confused??? Am I training wrong? Not sure if relevant: F53, not a beginner, 3x strength session p/w + other activities,aim is muscle build/retention.