It seems that this site (ipqualityscore.com) lists all of the IPs I have tried as Proxy/VPN. So I started thinking that it is just one of those sites that try to get you into registering and playing for some product. So I registered there to see what more options I would have. Only one option: Upgrade from free to paid 
Moreover I could not find any option to request any kind of review of an IP address. So the service seems that it’s not based on any feedback loop. Which in my opinion will provide too many false positives.
But I had to make sure before posting here, so I tried checking an IPs of Microsoft Office 365 email server (40.107.13.100 - mail-eopbgr130100.outbound.protection.outlook.com) . Guess what? That IP is also listed as a Proxy/VPN. For me that’s enough evidence that the site ipqualityscore.com does NOT provide accurate results.
I understand that this might feel slightly off-topic, but I though I would save a poor man’s time/money registering/using that site, at least for the purpose of checking IP reputation. If anyone feels that I’m wrong please say so.
I would suggest to check with some different tool, like MultiRBL.valli.org - Blacklist, Whitelist and FCrDNS check tool
P.S. 10 minutes later…
Your account was detected as a duplicate free account. Due to frequent abuse, free accounts are limited to 1 per user or company.
Access premium features by reactivating your account. Your account will be fully restored upon upgrading.
Which of course is not the case (registered with a true, valid email address belonging to a true and valid domain name).