look at the center growth ...

it is extremely fat and happy.. and has no blemishes ...

look closer.. and note the damage is on the oldest leaves ... and as such... it could have been transplant shock or mechanical damage when planting ...

frankly.. i only see one hole ... if there was a bug.. its probably long gone....

now.. if you start to see damage on newer growth.. than think about a remedy ...

there is an extremely active pepper forum... if you want to take your knowledge to the nth degree ...

BTW ... i gave up on cukes decades ago.. because they were a PIA ... if you fail.. shrug it off ...

post a pic of the other plant.. if the new growth is harmed ...

ken

Cristian, again your image does not show us enough detail to be sure what we're seeing. It appears that some of the leaves are knotched along the edges. If that's true, that can be a sign of weevils.

I can also see several small holes in the leaves but not well enough to guess what might be causing them.

I suggest that you go out to the garden after dark and inspect for sow bugs, pill bugs, earwigs, weevils, etc.

Ken must be looking at a different picture.

I'm not sure what insect pests might be in Melbourne, Australia although you may have many very similar to what we have. If you are not seeing anything that could be doing this during the day you will need to look at night.