Attiny85, high output impedance, dim leds
You already found your problem. I am answering only to provide some
insight on why you were experiencing the symptoms you had.

pinMode() takes two integer arguments (two uint8_t to be precise).
The names INPUT, OUTPUT and INPUT_PULLUP are just macros for 0, 1
and 2 respectively. This is why the compiler accepts your code with the
arguments swapped.

On the AVR microcontrollers, setting a pin's output register to HIGH
on a pin that is configured as input has the effect of turning on the
internal pullup. Thus

digitalWrite(pin, HIGH);


has the same effect as

pinMode(pin, INPUT_PULLUP);


on an input pin. When you do this, the pin will source (not sink) a very
small current. The pullup resistance is typically of the order of
30&nbsp;kΩ, and this is why you get such a small current.