To recover the grayed-out folders from the external hard drive on M1 Mac, we recommend you try iBoysoft Data Recovery for Mac.
It's likely that something interrupted the data-transferring process, resulting in the grayed-out folders on your Mac. You can run Disk Utility First Aid to check and repair the possible file system errors on the external drive. If First Aid doesn't help, the best bet to access the grayed-out folders is through iBoyosft Data Recovery for Mac.
It's a professional data recovery tool that has a good reputation for its recovery rate and usability. It can recover data from all kinds of external drives, including HDDs, SSDs, SD cards, USB flash drives, etc, connected to M1, M2, T2, and other Intel-based Macs.
Here's how to recover the grayed-out folders on the external hard drive:
Step 1: Free download and install iBoysoft Data Recovery for Mac.
Step 2: Keep the external drive connected to your Mac.
Step 3: Open the data recovery app, select your hard drive and click "Search for Lost Data."
Step 4: Preview files in the grayed-out folders.
Step 5: Check the box before the files you want to restore, then click the Recover button and save them to a different location.
To avoid folders being grayed out in the future, you can back up your data and then format the external drive on Mac. This gives it a new and complete file system. Note that you need to choose a file system compatible with macOS and select GUID Partition Map as the scheme.