On Windows 10,
mpv version 0.32.0-288-gee70e8ce50
and mpv-discordRPC version 1.4.1-UNKNOWN
I did not change any settings after installation.

When mpv is paused, Discord presence updates properly to show that the player is paused, but the remaining time continues ticking down, for around 15 seconds, after which, it jumps back to the proper time and continues ticking down.

e.g.:

• I paused a movie with mpv showing 04:22:47 left;
• Discord presence shows the paused icon but the "xx:xx:xx left" text continues ticking down
• Once the timer reaches "04:22:31 left", after one second, it jumps back to "04:22:45 left" and continues this countdown loop.

Everything else works fine i.e. the current timestamp ("AV:") does not change while the time left counter is ticking down.

Here's a screen recording from the Discord desktop app to better illustrate my issue (username and tag blurred for privacy):