I've been using dropbox cloud storage for 5 years now without any issues.
Mega is also another good cloud storage provider, but not as good as DropBox.
Although Google Drive is okay, I would not recommend them as they can easily flag your account even if the actual files are not illegal.
I had uploaded a few pictures of myself when I was a toddler that my mom sent me where I was naked from the waist down and one where I was a baby laying on a towel naked.
Well my Google Drive account was flagged for child porn and sexual abuse material, which was done by a bot and I lost my account.
I even had the police show up at my door and do an investigation and I had to go through court over the deal.
That's when I found out it was a bot and not an actual human that flagged it.
Although they were nude photos of a toddler and baby, the nude photos were of myself and were not illegal.
But I avoid uploading those now to any cloud storage providers and keep them on my own hard drive.
Naked photos of yourself or other kids are not child porn, just because they are nude, there has to also be intent and other factors in play.
Now if you have a collection of other peoples nude kids then that is classified as child porn, but having a few pictures of your own kids nude or even yourself nude as a kid is not child porn.
But you must also be careful and so you should never upload that kind of stuff to any public file storage.
Back in 2022 there was also a dad who took photos of his naked toddler for the doctor and google flagged him as being a criminal as they have automated tools to detect child porn and abusive images.