Code Completion popup works on every second key stroke

On version 2026.1.2 I've started to notice this behavior
when i want a object property, lets say CultureCode
when i write
o.C - there is a popup that hints CultureCode
then i press “u”, so its o.Cu - the popup disappears
then i press “l”, so its o.Cul - the popup displays again
and so on,
on every second key stroke - popup goes on/off

i thought it was a temporary bug, so i waited for 2026.1.3, it stayed like this
my current build is 
Build #RD-261.25134.178, built on June 14, 2026
it persists after the cache reset
it persists after the reinstall
it persist on different PC

if its an option i can toggle i cannot find it
there is no information about it and i can't fix it

can anyone help/explain to me whats wrong?
maybe i am doing something wrong?

thanks in advance