Visit these sites
http://www.powerlinenoise.com/
https://www.arrl.org/power-line-noise-faq
https://peerj.com/articles/1086/
https://www.pic-control.com/electrical-noise-interference-problem/
https://www.researchgate.net/figure/ECG-corrupted-Due-to-Power-line-Interference_fig2_252068169