Quick Question

Nope, chances are low, that is why are you not winning. There is no punishment for such script, only for autojoin ones - and that would get you banned, not secretly removed from pool when you get find out.
Recommendation: joining groups, increasing level

No, but giving games yourself raises your level so you get better giveaways.

Dont worry its not any fail cuz extension... i won 27 games in almost 8 years so... :D u winning game basically every month so u can say u are very lucky

The numbers of entries in public giveaways have been high in the last year or so, I would suggest you join some groups like unlucky-7 for better chances. The extended steamgifts plugin have nothing to do with it, there is no shadow banning as far as I can tell, you just wont see the giveaways of the people who blacklisted you

It's not related but advices to increase your winning rate
You have 4 way to increase winning rate
1.join groups they have less entries
2.do jigidis stuffs and join invite only games(=check discussions)
3.Be a good and active person and gain whitelists
4.do giveaways and gain levels and be capable to enter more giveaways

ahahahha comon i am level 2 and i won nothing in 6 years. It's a free giveaway site so just chill.