Plous (1993) defined confirmation bias as the tendency to search for, interpret, favor, and recall information in a way that confirms or strengthens one's prior personal beliefs or hypotheses.
When one gathers information selectively or interpret information in a biased way, that is confirmation bias in play.
Just take a look at the proponents of the 5G links to Corona virus and 20 pounds bill and their conspiracy theories. You will see how they tend to interpret ambiguous evidence as supporting their existing position even in face of superior evidence. Tweeps with this bias
often generate ridiculous evidence to support their claims. Confirmation bias is actually a problem when it becomes an impediment to accepting actual evidence.
Read the comments under this thread you will see how the best of us succumb to confirmation bias. https://twitter.com/toluogunlesi/status/1247215842334576648?s=19