I do not think that Apple has "removed" this feature – but they are using a different framework now to drive the displays on the M1 Macs (the same one used on the iPhones and iPads, actually). Since the feature to modify the resolution and HiDPI support *is* there, I believe it is only a matter to configure the proper files. Which ones, of course I do not know, let us hope that the developer of SwitchResX will find out which ones :-) I am an optimist.
mocen1go
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