External SSDs cannot properly be used anymore after upgrading to Sonoma

Two SanDisk Portable Extreme (one 1TB, the other 4TB) cannot be used properly after upgrading to Sonoma. A copying process of about 60GB to the 4TB SSD all of the sudden stopped. From that moment on the SSD couldn't be unlocked anymore (error notification popping up saying that the drive cannot be unlocked due to a problem with the drive - no further details). So I had to buy an expensive Data Recovery Software that worked on M1 and started recovering Video Footage and copying it to my other SanDisk Portable Extreme 1TB (it was the first time this one was plugged into the MacBook after Upgrade to Sonoma). Copying process went well. The second time I plugged the 1TB SSD in it would take long to load the SanDisk Unlocker, unlocked it, navigated to the folder where it would start loading the content of the folder for at least 15 sec (like an ancient windows 95). Load, load, load, then the drive suddenly disappeared completely from Finder without an error message or notification. Retried a hundred times. Sometimes it doesn't disappear but it loads forever(!) and I cannot preview files. When trying to preview a file it again loads for a minute or more and then fails to preview, sometimes the content of the entire folder just disappears in Finder. It's so weird. Other times the drive just disappears from Finder after a few minutes and a notification popping up saying the drive was not ejected properly. I have been working with these two expensive SSDs daily(!) for over a year on my MacBook Pro before the upgrade, and never had a single issue. Now after the upgrade to Sonoma I cannot use both of them.