APFS encrypted volume, how to get actual free disk space
Your disk has a capacity of 250.69 GB with 211.9 GB used leaving 38.8 GB.  The reported free space is 74 GB but 37.5 is purgeable. Purgeable space on a Mac is space that the Mac considers save to clean up. So while it says you have 74 GB available, 37.5 GB is currently in use but is safe to erase and clear off..