Samsung T7 SSDs and Monterey

This post is a "heads up" in case you encounter the same issue.

I have several Samsung T7 SSDs for projects that I carry these between my home and office machines. These were Mac formatted. Ever since I recently updated the Macs from Big Sur to Monterey (macOS 12.5), the Samsungs were very slow to mount. They also took a long time before you could access anything after they mounted. Almost like some sort of indexing was still going one. Once mounted, they performed well, until the next time. This didn't happen with Big Sur.

After doing some internet searching I ran across this fix, which appears to be the solution. First back-up any data on the drives, because you will need to reformat them. They must start as Mac, GUID partition. If not, reformat them as Mac, GUID. Once this is done, reformat them again as APFS. Then copy your data back to the drive.

The downside is that APFS won't be supported on older OS versions, but that's something I rarely encounter these days. In any case, it seems to have been the right solution for me.