Why my buds in week7/8 are not sticky as there were in week 5?

She looks ready to be chopped.

Hello mate, i see from your photos that the trichomes are ready, you have many of these amber so you should harvest your beauty :) Good luck and happy harvest!!

Yes, degrading because it is over ripe.

Possibly because of environmental conditions. You are growing outdoors, was it hotter and less humid during week 5-6 and now it's colder more humid? Drought stress is a known way to increase oil content. This stress starts when vpd goes above 1.2 kpa. Longer drybacks of your growing media would also lead to higher oil content. Where cannabis plants are from growing seasons are separated in a warm humid veg and a colder dry flowering period. In northern hemisphere it's just different conditions from what they really want, too cold and wet at the end