So, I was interested in the reason of the practice of bursting crackers in Deepavali since it seemed a strange practice to me and I was never explained the reason. I found this random article [1] on the internet last night that explains it by quoting an old literature: apparently we do it so that we can direct our ancestors that have come back on Earth back to heaven by lighting up the path (hence the fancy fireworks). Apparently, it doubled up to protect crops from bugs since they used sulphur in the crackers and sulphur has anti-fungal properties, etc. Not sure how trust worthy it is but makes sense ig.
1. https://thedal.info/significance-of-bursting-crackers-on-diwali/