Experiencing screen tearing and frame drops while using YouTube at 720p & above

i have an Intel core i3-7020u with no external graphic card and only the integrated igpu Intel hd 620 graphics
and i am experiencing serious screen tearing even on youtube if i watch any video at 720p or more
i didn’t have any such issues with windows

Is there any way to fix it ? ( i use manjaro kde)

Assuming you monitor is 60Hz, try reducing the refresh rate to 50Hz then change it back to 60Hz, that solved a similar issue for me.

Have look here: https://wiki.archlinux.org/index.php/Intel_graphics#Tearing