External Thunderbolt SSDs not showing space after deleting files

I have two external Samsung X5 2TB Thunderbolt 3 SSDs. Both of them work fine after I reformat them. But when I delete files (and empty the recycle bin), the space on them does not increase. In order to get space back, I need to empty it, reformat, then rebuild up files on it. So far I have tried the following: 1. Enabling TRIM. It's enabled, does nothing. 2. Showing hidden files/folders to make sure nothing is hiding on the drive. There's nothing there, trash on the volume is empty, etc. 3. I've tried running "First Aid" in Disk Utility. It runs fine and finishes but it doesn't fix the problem. What could be causing this? I am running MacOS Monterey on an M1 Max laptop.