why this glitch an how to get rid it

how to get rid of this glitch??

my system is running plasma 5.6.3:
PC=Dell latitude E6510, RAM=8Gb, GPU=GT218 NVS 3100M, CPU=i7 Q 720 @ 1.60GHz
upgraded 13.2 to leap 42.1, using wolfi repos. I’m running KDE 4.14.18 and plasma 5.6.4, KDE frameworks 5.22.0, KDE applications 16.04.1, Kernel 4.1.21-14-default