Fertile Window prediction seems a little early?

Jasmine-Rae • I’m a Mumma to 2 little ones ✨ Would love more though 🥰
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.