Unreliable connection to my phone's WiFi hotspot

Sorry, this almost surely isn’t it, but just in case - have you disabled Wi-Fi Powersave on your laptop? When I had issues with my Wi-Fi on Pop!_OS, it didn’t manifest as high latency as this post described, it caused periods of constant dropped connections like you’re describing, so I thought I’d just mention.

https://discussion.fedoraproject.org/t/tip-lower-wifi-latency-by-disabling-wifi-power-management/74534