Here’s an even easier way!
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Make your clothsim the way you want.

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Select your object and go to
File > Export > Alembic (.abc). Make sure to selectOnly Selected Objects -
Go to
File > Import > Alembic (.abc)and import your file you just exported. -
Select
Override Frameand add a keyframe on frame 0, setting the Override Frame to 150. add a keyframe at frame 150 as frame 1.
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In the dope sheet (found in the Animation workspace tab by default), set the keyframe interpolation to Linear. Disable Only Show Selected button (is this a bug?)
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Enjoy your reversed animation!


