QSWAT

This version of QSWAT will run with QGIS versions 3.16 and later that use Python 3.7, 3.9 or 3.12.

It replaces QSWAT3_64, QSWAT3_9 and QSWAT3_12. If you have any of these installed you need to use the plugins menu to uncheck it and choose QSWAT instead.

1.7.2

QSWAT3_12 is for versions of QGIS 3.34.6 or later that use Python 3.12. This is the default version to choose if you are unsure.
QSWAT3_9 is for versions of QGIS at least 3.16.14 and at most 3.34.5 that use Python 3.9
QSWAT3_64 is for earlier versions of QGIS that use Python 3.7

QSWAT

QSWAT3_12 is for versions of QGIS 3.34.6 or later that use Python 3.12. This is the default version to choose if you are unsure.
QSWAT3_9 is for versions of QGIS at least 3.16.14 and at most 3.34.5 that use Python 3.9
QSWAT3_64 is for earlier versions of QGIS that use Python 3.7
QSWAT3 is for earlier 32-bit versions of QGIS that use Python 3.7 and with 32-bit versions of Microsoft Office