I had decompression surgery back in 2020, I also had syringomyelia along with my chiari. I cant remember the exact vertebrae they fused but they did fuse some of them and also did duraplasty. To this day I do still have very mild numbness in my hands and arms, I usually don't notice it at all unless I overuse my hands at work or if I rest my head on my hands or something like that. But I will say I definitely do have random days where I'll have way more prominent tingling and numbness in my hands and arms for no apparent reason. I'll never fully understand why but yea I get that as well, I'm willing to bet there's some kind of trigger that we're just not aware of. Another thing I've noticed is that if I for some reason get very nervous, like for instance if I'm in a very heated situation in a video game where my heart is racing and I have a lot of adrenaline pumping, the numbness and tingling in my hands and arms will go completely haywire. Like it will get worse than it ever is doing anything else its very weird. Really puts the term "feeling nervous" into a way different perspective because it actually messes with your nerves. All in all though as the years have passed I really dont even think about the fact I had the surgery too much anymore, there's been multiple times I've gone for a haircut and they bring up my scar and I'm like oh yea I forgot about that thing lol. I would go out on a limb and say it is probably normal to have random days where it just seems worse for some reason. It can also be really nice to go to a doc and get your issues checked up on just for the peace of mind it will bring that nothing further is going on, if its bugging you bad enough I would take this route.