When Illustrator is closed, it forgets the color model that was chosen for exporting JPEGs with Export for Screens.

For reference of how this setting is accessed:
File > Export > Export for Screens
Then in the Formats area, click the gear icon.
In the column, select any of the JPG formats (JPG 100, JPG 80, et cetera).
Then there is a drop-down labeled "Color Model" that allows you to choose between CMYK, RGB, and grayscale.

If you select RGB then click "Save Settings" it will remember the setting while Illustrator is open. But when you close Illustrator, and open it again, the setting will be reverted to CMYK when you are working in a CMYK document.

This is rather annoying for me because I work in the exhibit design field and graphic layout are intended for print (CMYK) but often need to be visualized in 3D models which require RGB images. So exporting to RGB is essential and having to change the setting frequently adds more hassle to the process.