My $0.02
It has been years since any of the major e-bike manufacturers has had a safety recall due to a battery defect (please correct me if I am wrong, but the last one was in 2015 with respect to some Pedego batteries). In the meantime quite literally millions of e-bikes have been sold.
My own opinion (and you can and should take it with a grain of salt) is that the risk of a battery fire is tiny unless the battery has been damaged (which usually means it has been dropped), someone has made unauthorized modifications to the battery or the charging apparatus, or it is stored in an extremely hot location. I'd personally be more stressed about leaving batteries in a hot car on a sunny day than by charging it overnight.
Worldwide, I'd guess in that last three years hundreds of e-bike riders have had fatal accidents. I doubt there have been more than a few dozen battery fires, and probably no more than a handful that have involved name-brand bikes or batteries. So if you want to focus on risk consider what is happening when you ride, not what happens to your bike when it is parked in your garage.