So here we are again, and it's not a surprise that the Warp stabilizer plugin is doing something completely different to a clip in a project that was analysed in the previous version of Premiere (it's happen before after upgrades). I've attached a clip so you can see how the clip is now playing in premiere 13.1 along with a screenshot of the effects control.

So in 13.0.2 I had a single clip in a sequence (this was 1 weeks ago just before upgrading to 13,1).
I applied warp stabilizer
I then keyframed the rotation and position to fix a few little issues.
After this the guy in the clip was dead centre the whole time (see the video and you can see a kitesurfer and he was in the centre throughout).

How I've opened the project in 13.1 and you can now see that the clip moves around all over the place. It looks like the archor point is maybe being interpreted differently in 13.1 in relation to the warp analysed data.

I have seen this before and submitted bug reports for it on a couple of occasions. I believe it happened when upgrading from 11 -> 12. I have ongoing projects with hundreds of clips which use Warp stabilizer and it is impossible to use them in new versions of Premiere because the clips fly around all over the place now.

Hopefully something can be fixed for this