I have an update.
The Surfshark that I was using was from the Google Play Store. It was version 3.15. I uninstalled it. I re-installed it from the Formular Market. This version is 2.8.4.5. It works a lot better. Wired speed is 290Mbps download (still not great but usable) and wifi speed is 249Mbps. These are both with the Wireguard protocol.
Hope this helps someone.
Thanks for your update. You help a lot of surfshark users now temporary. Good job my friend. I use Nordvpn, so no problems here