The Signature element is the RFC 2104 HMAC-SHA1 of selected elements from the request.
But wikipedia says that sha1 is not safe anymore:
As of 2020, chosen-prefix attacks against SHA-1 are now practical[8] as such, it is recommended to remove SHA-1 from products as soon as possible and use instead SHA-256 or SHA-3. Replacing SHA-1 is urgent where it is used for signatures.
https://en.wikipedia.org/wiki/SHA-1
There is also a benchmark where a guy bruteforces sha1 at a speed of 68771.0 MH/s! https://gist.github.com/epixoip/a83d38f412b4737e99bbef804a270c40