This happens especially with DMG plugins. If I open Studio One on a smaller, primary monitor, then open a DMG plugin on a larger, second screen, the plug-in GUI is rendered at 2x size. If I click another plug-in in the same chain by clicking the tab of the next plug-in, then back to the DMG plug-in, all is fine.
Mac OS 11.2.3, Mac Mini 2020 (Intel)
Studio One Pro 220.127.116.11799