December 23rd I logged into Zwift and got a message that I was way beyond level 25 and my points would accrue rapidly to advance my levels. And the points came in fast! I was getting 240xp per mile for the short ride I did that day. But on the 24th I was back to 30xp per mile and still only partly through level 25. What happened to the fast accrual?
Take a look at ZwiftInsider’s explanation of accelerated leveling for riders whose experience exceeded Level 25 at the time that the Level 50 update rolled out. See if that explains your acceleration coming to an end.
Yes. That is the answer. Turns out I wasn’t actually very far beyond level 25 so I burned through the accelerated leveling in one ride. Thanks for that link.