Mirroring + Quicktime Player + MacBook Pro freezes ... the miracle workaround and the impending failure

For many years, my partner has given talks that mirror a MacBook Pro's QuickTime Player onto an overhead projector. And for many years, this ALWAYS "just worked" ... no matter the projector, no matter the connector. It's been WONDERFUL.

Then the covid pandemic came, and talks were given by Zoom. But no problem: for the last two years, Mirroring + QuickTime Player + Zoom ScreenSharing has ALWAYS "just worked".

Now the covid lockdown is ending, and live talks are resuming. And a HUGE problem has emerged: now Mirroring + QuickTime Player NEVER works ... no matter the projector, no matter the connector. Everying looks OK for a few minutes ... then the system begins to slow ... clicking becomes unreliable ... the system freezes ... and a hard reboot is required.

This freezing problem has been reported multiple times on this forum. Moreover, facilities managers have confirmed to us that freezing is commonly occurring---unexpected & disastrously & before large audiences---to Apple-equipped presenters who naively expect their MacBooks to "just work".

INSTANT WORKAROUND (for Zoom Pro subscribers): fire up a one-person Zoom session, share the screen, and mirror the screen onto the projector. No freezing will occur ... bacause for no obvious reason, the Zoom ScreenShare mitigates the QuickTime Player + Mirror freeze-ups.

THE IMPENDING FAILURE: eight days from now, we are scheduled to give at talk at a facility that has no internet connection. No connection -> no Zoom session -> no workaround.

Yikes! Can anyone in the Apple Discussions provide an alternate workaround? Apple, can you PLEASE fix this longstanding mirror-freezing issue .... which is making the Apple brand look bad in front of large audiences?