EDITED
Just tested BUG2 again 5 minutes ago on own site. It's the same on flynax demo of course.
There are 2 plans with different active duration available for customers: 1 month plan and 2 month plan
Case 1 when current plan (1 month) has less day than plan you extend (2 months)
I posted ads using 1 month plan. Go to my-ads and extend using the 2 months plan -> I got 4 months. It should be 3 months: 1 month in 1st paid and 2 months in second paid.
Case 2 when current plan (2 months) has more day than plan you extend (1 month)
Continuously, with the same plan that has 4 months active day earlier. I extend it will the 1 month plan -> I got 3 months and 29 days: 4 months subtract 1 day. How come you paid for 1 more month but get 1 day subtraction from your current plan.
I hope this is simple and clear.