Hello, I see this same issue when using VMware Fusion as well. Was hoping that Parallels would not have it but it does. My host is OS X Catalina, as is the guest (build from recovery partition). On the guest, whenever I use multiple tabs (finder or safari but not Chrome) the tabs look terrible. I have attached screen shots Thanks in advance for any and all help. Mark
Oh yes, looks familiar. I wasn't sure whether this was Parallels or the fact that I connect to the host Mac via screen sharing.
Hoping to find a solution or work around on this. I will say one thing, Parallels BLOWS AWAY VMware Fusion when it comes to speed. Also when I monitor the host (top from shell) Parallels uses minimal resources in comparison to Fusion.