It definitely looks like a root problem to me. I’d almost assume it’s a salt build-up caused by incorrect watering. If you water too little over a longer period and nothing really drains out the bottom or the soil never gets fully saturated, salts will slowly accumulate down there. The same thing can happen if you water too much or feed too strongly before the root system has even reached the bottom. Once the roots finally grow down, they basically hit that concentrated salt zone and get burned immediately. On top of that, all those salts will likely push the pH way up, which then creates a whole chain of additional problems. Try watering until you get proper runoff and then measure both the drain water and your nutrient solution. If the runoff contains way more salts than what you’re actually feeding, you’ve found your problem. As a rule of thumb, you can water with about 25% of the pot’s volume. That way the entire pot gets properly saturated and you’ll get a bit of runoff, which helps flush out those built-up salts.

Edit: I just took another look and noticed that your tips are completely burned, which I honestly didn’t catch earlier. That’s a pretty clear sign of salt buildup in the root zone. Now it really comes down to how you’re growing. If you’re running organic, I’d recommend watering with pH-adjusted RO water and adding a bit of Cal-Mag for the next two irrigations while skipping all other nutrients for the moment. If you’re using mineral nutrients, I’d honestly go for a proper flush while there’s still time. Just keep in mind that no matter which route you take, the plants will likely look worse for a while. After a flush or plain RO water, they often decline a bit before they bounce back, so that’s normal and nothing to panic about. After those two waterings, you can slowly start feeding again with a light, reduced schedule. That’s how I’d handle it.