I have difficulty playing etudes on a piano which has heavy irresponsive keys

[claireliii]

I usually practice on a upright piano and the keys are really light. I can usually run through an intermediate level Chopin etude at its original tempo. however, I always have problem playing on my teacher's Kawai grand. It is the heaviest, most irresponsive piano I have played on, and I have actually played on a lot of grand pianos (steinway/yamaha/cb...)before, since I usually practice at school before the pandemic. I always found it more more tiring to play with heavier pianos, and sometimes my fingers get so tired that I can even run through the entire etude.

My teacher told my that it had nothing to do with the piano but my way of exerting strength. my fingers were too loose and my wrist was too tight, and Id need to rely on my major knuckle more.

my background is not very solid, I did not grow up practicing more than 1 hour every day and I have been criticized of fingers being too weak. However, I am really serious about piano now and seriously hope to play through an chopin etude at a satisfactory level to prove to my teacher that I am not so incompetent.