>>12014750
Because retroarch is shit and it needs to reopen the window to switch the res. So it fades out because the 240p source is closed, then changes it to 480i with a new window that is being put on fullscreen. It should just blink in a split second like MAME or arcade OSD does, but as I said, retroarch is a piece of shit full of bloat unfinished features, with CRT switching being one of them (they still have 3 nonfunctional settings related to it, sitting for over 6 years with zero time put into them).