Fertile Window prediction seems a little early?

Jasmine-Rae • Have 2 little ones, one day I may have another one if I can find the right person to settle down with that treats mine like his own ♥️
Not sure why this cycle has changed, but Glow is stating my fertile period started Yesterday, yet a day before that my Monthly ended. Every other cycle Glow wouldn't alert me that my fertile window was here until about a week and a half after my monthly ended. Why is the prediction so early this cycle? I'm a little confused.