I believe that Martina doesn't have the connection she would like with Steffi nor a true understanding of her, so she does what she seemingly always does: she opens her mouth and makes comments that don't endear many people to her. I don't write that to attack Martina but rather to point out what I see as patterned behavior. For example, Steffi is a private person who appears to be very careful in selecting whom she puts around her and who makes decisions with a lot of reflection. She is not media-hungry, she didn't seem to bask in the feeling that she was better than others, and she appeared to keep many of her inner opinions to herself. Martina consistently puts herself in front of the TV cameras, frequently compares herself and her game to others' games (Steffi played to be as good as she could be herself), and shares her opinions freely.
Steffi and Martina are both incredible athletes and they both achieved a lot during their tennis careers, but as people, they have many differences. If Steffi is bothered by some or a lot of Martina's behavior, she doesn't mouth off about it very much. Martina, though, speaks a lot about her perceived beefs with other people. Sometimes, I think she is absolutely right. Sometimes, she doesn't know what she's talking about.
If Steffi tried to be a blatantly PR
-savvy individual (I'm not stating she isn't PR
-savvy, just that she is not flashy or fake about it) who stayed heavily involved in the tennis world in a very publicized way and who was more talkative with a greater number of people... if she was more open about her decisions to do this or not do that... if she engaged in playing GOAT games... I think Martina would be one of her friends and Martina would not judge Steffi so harshly. The reality is that Steffi is who she is: fairly private and content with her current role as a wife and mother. Martina does come off as bitter when she makes negative comments while the other person in question is silent or not part of the picture, but she has the right to open her mouth whenever she wants.
Just some thoughts.