Automatically disable your secondary Wi-Fi when your primary Wi-Fi connects, and enable it when the primary disconnects.

30-wifi-failover.sh

#!/bin/bash
# /etc/NetworkManager/dispatcher.d/30-wifi-failover.sh
# test:
# sudo bash -x /etc/NetworkManager/dispatcher.d/30-wifi-failover.sh wlx... up

# --- CONFIGURE YOUR DEVICES HERE ---
PRIMARY_IF="wlx..."
SECONDARY_IF="wlp0..."
# -----------------------------------

# The script gets two arguments:
# $1 = The interface name
# $2 = The action (e.g., "up", "down")

IFACE="$1"
ACTION="$2"

# We only care about events from our primary interface
if [ "$IFACE" != "$PRIMARY_IF" ]; then
    exit 0
fi

case "$ACTION" in
    "up")
        # The primary interface just came UP (connected).
        # We must disable the secondary interface.
        logger "NM Dispatcher: $PRIMARY_IF is UP. Disabling $SECONDARY_IF."
        nmcli device set $PRIMARY_IF managed yes
        nmcli device set $SECONDARY_IF managed no
        ;;
    "down")
        # The primary interface just went DOWN (disconnected).
        # We must enable the secondary interface as a fallback.
        logger "NM Dispatcher: $PRIMARY_IF is DOWN. Enabling $SECONDARY_IF."
        nmcli device set $SECONDARY_IF managed yes
        nmcli device set $PRIMARY_IF managed no
        ;;
esac

exit 0