This is generally how it is with ISO, @maridmc friend!... The higher the ISO, the more "digital noise" there will be, but also greater sensitivity in the sensor, which allows for faster shutter speeds and therefore avoids camera shake. It's certainly great that you're maximizing your use of your camera's manual controls to take photos more according to your desired standards and get the most out of your camera... Good work!...

P.S. By the way, yesterday I shared a POST with photos taken with a small camera I bought in 2009 and found stored in my studio... You might see some interesting information in that post, as I included some parameter data I used at the bottom of each photo I took as a recent experiment with that nice little camera I thought I'd lost...

!discovery shots
!PIZZA

Keep going, your talent is high, I know!