With back braces, the commonality amongst them is that they bind around your lower trunk, provide some mechanical support, and provide some feedback for the joints and tissue of your back. There may be some with lighter and more breathable material, but each of them will likely get pretty sweaty if you’re active in the heat.
From a physical therapy perspective, back braces can be helpful in an interim basis but will not be a solution for your lower back pain. What will be more likely to resolve your pain and spasms will be to get your back moving better. When you have had an episode of pain in your back, your body has a strategy of bracing and limiting movement. Often, this strategy continues even after the pain eases, and it typically will make the pain and spasm more likely to occur going forward. It can be quite disabling, even when the underlying issues in the back are not serious.
I feel my best advice for you is to seek out a good PT with orthopedic or manual therapy specialization and credentials. They should be able to mobilize your back, get your muscles working more appropriately around your spine, and above all, give you fluidity and confidence with movement. It may be that something like a brace or strapping may be helpful on an interim basis while you are learning to move better or if you are especially more active than normal. The goal of anything that limits or restricts movement should always be to progress out of it when the body is ready.
It may take some work on your behalf to get there. It may feel like putting on a brace is an easy solution, but good PT is very likely the best way moving forward for you to manage your back.
I have to include the caveat that without doing a detailed assessment of your back, it is difficult to give clear and accurate direction and advice. I have seen many patients with a similar situation that have done great with PT. If you look up ‘find a PT’ on apta.org you may be able to connect with a good physical therapist.