I had been in contact with the support team through e-mail about this issue and it was solved itself right after last maintenance/patch. The problem came back again right after after today's maintenance. I just wanted to write this to see if others are also experiencing this issue lately.
-I opened necessary ports on router.
-My antivirus is disabled.
-Contacted with my isp and switched to static ip, there doesn't seem to be an issue regarding the isp because I have 0 connection problems outside loading screen(and 0 ping spike issue or disconnects outside the loadingscreen ingame).
-This loading screen problem doesn't occur when I use VPN.
The thing that led me think that it's rather game related is the problem coming back again right after this maintenance patch and that was solved after the last week's.
I hope you can take a look at this problem. Thanks in advance.