Hello,

this is not a big problem, but for me makes a board useless

I use orange pi to control ralays thru GPIOs

it works flawless on Orange PI PC, PC+, One

so I decided to buy Orange PI Lite and I discovered that all gpio are set to high for half a second and then back to low, while unit power up or restarts. Just like an internet router

It do that even without a SD card, that points this is coded  into U-Boot.

Any idea how to fix that?

I doubt that OPi Lite is reacting differently than OPiPC/PC+/One, they are using the same SoC.

Since GPIOs are left floating until been initialized as output, your relay driver circuit must take care of that unknown state using pullup or pulldown.