What r the chances of infections or anything if I have a 3rd muscle repair in stomach? I had a tummy tuck and 2 muscle repairs in 2 years

Agree. I agree with dr berg. To need a 3rd surgery after tummy tuck is rare. Something like a ct may be worth getting to look at the musculature and make sure something else is not going on.
3 strikes? If your diastasis repair has recurred twice, i would stop sit back and analyze the situation and ask why did it recur. It is due to: recurrent pregnancy, weight gain, or possibly technique or improper diagnosis. This may be more of a hernia or improper diagnosis and subsequent treatment. Make sure you are close to your ideal body weight and understand core strenghtening then seek a specialist.
Get a SECOND opinion. Sounds like you have had plastic surgery with the tummy tuck. It is not uncommon to also have a plication of the rectus muscles at the same time. Plications are not true hernia repairs, but they can fail. If this is your situation, then you should get a second opinion. You might not need anything at all. With redo surgery, there is increased risk of all surgical complications.
Maybe not. Re-operating to fix a muscular repair is very uncommon. Why you would want a third such operation is concerning. The risk may exceed the benefit here and i would encourage you to talk about this with your surgeon before just having that third operation.
Rare. Your history of requiring 3 “muscle repairs” is certainly unusual. Revisionary surgery carries many risks; risk of infection specifically fortunately is low assuming careful selection of plastic surgeon and appropriate location of procedure ( fully accredited surgery facility). Your plastic surgeon will be able to address your concerns more specifically. Best wishes.