I have had the same issue since upgrading to Venture. Here are my details.
MBP Pro M1Pro
Ventura 13.4
Lightroom Classic 12.4, eject after import unselected.
CF Express B - Delkin 325GB, SanDisk 128 GB
The issue is intermittent, I can't determine if it's the timing of opening/closing LR, other open apps, or the time between reboots, etc.
Basically after mounting the CF Express card, opening LR, importing selected files, close LR import completed
Open Finder and select CF Express card, on occasion, I can read the folders, and I can then reject the card. However, if I can't read folders the beachball starts. My only recourse is to manually eject the card and I'm good to go.
I have never had an issue with any SD card import/reject using LR.