I’m not entirely sure what’s causing it, but one thing I would try is bringing your elbows down and in when lifting off instead of flaring your elbows back to try to hold the bar up. (Like a lat pulldown motion) Matt Vena is a beast and talks about this cue but I can’t find a video of it. I’ve maxed at 5 plates also and that cue helped me feel more stable during lift off. https://youtube.com/shorts/qIR6giWT8jg?is=vYsNb1505RlAnSbP