Submersible pump trips the FI (residual current) breaker when turned on

Hello everyone,
I bought a submersible pump (model 30136). When switched on, a residual current circuit breaker always trips. I complained to the manufacturer and received a new one. The new one has the same effect.
Now I thought it might be my power supply/wiring. I checked again and could not find any error.
Then I got another pump (from a different manufacturer) with almost the same power (900W instead of 950W). This one works perfectly.

Could it be a series defect of the pump (manufacturer)?
Does anyone have a tip for me?
THANK YOU all.

You have already given yourself the tip. Try other manufacturers.

I just wonder, why do you protect a submersible pump with an RCD?

You have already given yourself that tip. Try other manufacturers.

I just wonder, why protect a submersible pump with an RCD?

Well, the outdoor socket will surely be protected by an RCD...

Would someone have a tip for me?

FI LS installed and starting current of the pump too high? Try hanging one or two cable reels between the socket and the pump and try again. I can't imagine a serial defect. It has consistently good reviews.