Which mattress topper helps most with lower back pain?

I have been trying to deal with some annoying lower back pain and I am starting to think my mattress topper might be part of the issue. The mattress itself is still decent but the topper I bought a while ago feels like it is either too soft or too uneven. I wake up feeling like my lower back is sinking a bit and it gets worse on the nights I toss around.

I do not really want to replace the whole mattress right now so I am hoping a better topper could help. I sleep mostly on my side but sometimes end up on my back. I am not sure if I need something firmer or something that distributes weight better.

If anyone has tried a topper that actually reduced their back pain I would love to hear what worked for you. I am just trying to get through the night without waking up stiff every day.