A lot of things can affect an SSD's performance. The third party software you have installed on macOS can easily impact system performance. Usual culprits are anti-virus apps, cleaning optimizer apps, and third party security software....none of which are needed on a Mac. If you post an EtreCheck report here, then we can review it for possible clues.
If you recently put data on the external drive, it is possible Spotlight is still indexing the external drive.
Make sure to disconnect all other external devices in case one of them is causing a problem.
Make sure to connect the SSD directly to the Mac.
Try using another USB port especially on the other side of the laptop. And try using another USB cable and even another adapter if you must convert the port to an older USB-A style connector. You want to use good quality USB3 cables & adapters....make sure they actually support USB3 (ideally should support USB3.1/3.2)....it is hard to tell with cables since they are not clearly marked (the Apple cables will have a lightning bolt icon on the USB-C connector to denote Thunderbolt 3 compatibility which also indicates USB3 compatibility....some other brands should mark their Thunderbolt 3 cables in the same manner). Good USB3 rated USB-C cables should at least have the USB trident symbol on them along with their speed designation such as "SS 10" meaning Super Speed 10Gb/s. Any USB-C cable without a Thunderbolt lightning bolt symbol or USB trident symbol should be avoided. Manufacturers don't always provide very good cables with their products (some do and some don't).
What file system is being used on this external SSD?
Are you using any proprietary third party software from Kingston to manage the external SSD?
Have you recently written any large amounts of data to the SSD? SSDs can slow down to a crawl if lots of data has been recently written to the SSD. Some SSDs may take a long time to recover after that occurs.
What is the exact make & model of the SSD? Provide a link if possible so we don't have to search for it since many times there may be more than one similarly named model.
Not all external hardware is necessarily compatible with an Apple Silicon Mac (usually older devices) or even some versions of macOS.
Are you syncing anything on the Kingston SSD to the cloud? This can cause poor performance of speed tests.
