This is a common problem for VPN users regarding cashout since their page is updating slowly due to a lot of players "from the same IP" getting rate limited. This was explained to you by support, I recommend not using a VPN in the future if you want more reliability around cashing out.
In the end, youre claiming at the exact moment the cashout was accepted, Karatzev was 1.75 and Swiatek was 1.3. Darko says Karatzev was 3.5 and Swiatek 2.1
If Darkos numbers are accurate, then your 2700 payout wasn't a glitch, it was just an offer with almost 40% vig (cashouts are almost always horrible 40% is believable from what I've seen offered).
If your numbers are right you should be able to line up the time the cashout happened with the current state of each match in real time. Both Karatzev and Swiatek went from favorites to underdogs at some point, and it happened before Sinner started to melt down, but after your bet was cashed out.
Also, don't blame your vip host or argue with them about this. It's not their fault, there's nothing they can do, and it's just dumb to be anything but nice to them.
This is exactly it