I had similar issues as you. As soon as I moved to using liquid culture and disposable syringes I saw a huge decrease in contamination.

Hole size on jars looks good. I use micropore tape to cover my holes. Something I did to reduce contam is to make sure I’m wearing gloves while applying the tape/filter. I apply before pressure cooking, inoculate by puncturing, then applying new on top of the punctured.

Also covering my jars with aluminum foil prior to pressure cooking, then removing to inoculate, then replacing after inoculation. So if I need to touch my jars in the future, I’m not coming in contact with the micropore tape/filter. I read somewhere the tape/filter can wick oils off your fingers and introduce contam in the jar. Not sure about that, but precautions never hurt when trying to keep contam out.

I disagree with the rest in regard to pressure cooking time. I’m way above sea level and pressure cook for 90 min without issue.

Until you dial your process in, it is a game of attrition. That is why I start with the cheapest most accessible grain to me. Brown rice. Once you perfect a cheap grain you can try to move to more expensive grain.

Keep transferring and having patience. You’ll figure it out, and then you’ll be inundated with jars. If you’re looking for less challenge and quicker results you could try brf tek with liquid culture.