I'm not quite sure what you meant in the 2nd para. But I find it interesting that multiple probes showed the same effect. It's so compelling I wish they would send some missions specifically to test this even more precisely.

The obvious parallel was https://en.wikipedia.org/wiki/Pioneer_anomaly which was finally solved. But who know at this point?

Personally I think GR has to be "wrong", since it conflicts with QM, and if the 20th century showed us anything it's that QM alway wins.