Altitude Gain with full speed in ALT hold - not becz of Vibration

Hi Guys, I need help here.

I am testing my micro 4" inch quad with:
[Flywoo F745 Nano FC](FlyWoo F745 AIO BL_32 — Copter documentation
Matek M8Q-5883 GPS
1800mah 2s Battery.
AUW = 250g
Arducopter 4.1.5

I just finished the initial setup and configured the PIDs according to the initial parameter setup tab in the Mission planner. No Autotune nothing, only testing in my room. I armed, and increased the throttle it was looking good. Suddenly it started drifting away a little with a bad AHRS warning message on telemetry. I landed and increased throttle again and it was looking all good. I flipped the switch for altitude hold and boom, it skyrocketed to the roof and crashed to the roof. I disarmed the quad, and it fell down. I checked the logs and seems like vibrations are not the cause of this issue. Vibration increased after the RCOUT went full.

I am not able to find out the cause of this. Can anyone please help me to find the problem?

Params: params.param (18.5 KB)

It’s because you are indoors. AltHold uses the GPS for vertical velocity by default

I agree.

I recently switched by RX from crossfire to ELRS, and video transmitter. I had changed firmware and again flashed ardupilot and loaded backed up params. Earlier it flew nicely on alt hold indoors too. Same firmware, same params, same FC.

Now I wonder how it worked earlier and how this happened now. Not getting Z velocity from GPS made It shoot to full speed?