A few months ago, I have assembled a new PC.
13900K / RTX 3090 / MoRa 420, Dual-Pump (same type, same speed), 500mL reservoir, Leakshield, High Flow Sensor, Radiator in/out temperature sensors, Aquaero 6.
At setup, Leakshield complained that dual-pump configurations are not really supported: "With more than one pump in the system, the function of Leakshield cannot be ensured". That is fine, I chose the "Monitor" function.
Until a few days ago, everything was fine. With ambient temperatures becoming higher, I started the room AC (to 26 degrees ambient), and if the AC is on, and I play a more demanding game (Starfield, World of Tanks, Cyberpunk 2077), after a short while since the game starts, Leakshield starts the alarm complaining about "frequent pressure drop". Obviously, there is absolutely no leak, I have checked repeatedly.
The first time it happened, I assumed the reservoir liquid level was to blame (the reservoir was only 65% full), so I topped it off to 98% full (leaving enough air to compensate for liquid dilating). The result was the alarm started much faster than previously, after I started the game.
Relevant information:
Loop Liquid volume: around 2L.
Pumps: 2x D5, always at 100% speed.
Flow: 250 L/h
Liquid temperature at idle: 28.3 degrees Celsius at Radiator exit, 28.4 degrees Celsius at Radiator entry.
Fans: 4x Noctua 200mm fans at 513 RPM, set to increase slowly once liquid reaches 35 degrees Celsius (that never happens if AC is on).


Which settings should I change to stop alarms from going on unnecessarily while the system is under load?

Well... I guess it's not important.
Consider the matter closed.