I agree with @Doug Stevenson. The upload speed is determined by various factors, including the protocol used, available bandwidth, network latency, and the size and quality of the images or videos being uploaded.
For Cloud Storage for Firebase location, you must consider choosing the location of your bucket close to you to reduce latency and increase availability. (This post might give you insights)
If you are uploading using Firebase Client SDKs, the upload speed is slower compared to using gsutil. This is because, unlike the direct communication between gsutil and Cloud Storage, the SDKs must evaluate Security Rules, which introduces latency due to the time spent on these evaluations.
You can also try reducing the size and quality of the images or videos, as well as increasing your internet speed. (see this post)
For ways to track upload progress and other useful methods, check out these blogs :
I hope the above helps.