On deadlifts I nearly faint when I go down. I get that this happens a lot when you lift heavy, but I’m not lifting heavy. Not even relatively. It’s 65 pounds which is nothing to me. When I first started I didn’t get lightheaded, but now even with 65 for a warmup I’m dizzy. By the time I go to my main workout, I go to 75 or 80 and at this point I’m about to black out after like 2 reps. Again, not heavy but something is still wrong. I think my form is correct. Deep breath with belly expanding on inhale, brace, and squeeze glutes.
I also want to progress with chin ups, but I can do neither pull ups, chin ups, and even lat pull downs aren’t doing anything - the pull downs I feel in my upper back, and then my forearms get super sore even after leading with elbows. I’m doing a chin up grip on pull downs with ‘hooks’ (thumbs on the same side as other fingers). I tried negatives briefly, but the pull up bars are at an angle, and there were too many people at the squat rack which is the only place with straight horizontal bars.
Are you using a diaphragmatic breathing technique / brace when lifting? The idea is to breathe in a bit, then hold it with your diaphragm (kinda like when you've gotta push hard to do a poo), and only then do the rep. This helps you keep blood flow consistent to your head. One hypothesis for why you're getting lightheaded is that you're putting pressure on your vagus nerve, something that can happen just be flexing your neck muscles really hard. You can actually make yourself pass out by squeezing your neck muscles too hard. Breathing technique will help prevent you from relying on your neck muscles too maintain posture when lifting.
Also be careful - I'd recommend having a strong partner to spot you if you do deadlift in the future just in case you do actually pass out. You don't want to hit your head on anything - your spotter could catch you.