Stage 5 is probably the big difference maker. Stage 4 looks like it's a 21km road stage that just goes over a (not especially threatening, mind) mountain from San Gil over to Hernán Buenahora's birthplace of Barichara. Mexico's Anet Barrera - teaming with today's stage winner Diana Peñuela - was 4th last year and is the best rider from last year's (tougher, including an HTF and two MTFs along with a near 30km ITT) Vuelta a Colombia Femenina to be present; winner Lilibeth Chacón was taken out by a collision with a dog at the Bolivarian Games and is recovering from a broken collarbone, while 2nd placed Aranza Villalón and 3rd placed Miryan Núñez are both trying their luck in Europe with Spanish teams this season. Obvious names to keep an eye out for are Lina Marcela Hernández who was 2nd today, she was 3rd on GC in 2020 and is still only 23; stalwarts of the Colombian scene like Ana Cristina Sanabria (three time winner of this race), Jenny Colmenares, Liliana Moreno and Estefanía Herrera; and 19-year-old sensation Carolina Vargas who I know nothing about but can see has taken a big step forward this season, won the Vuelta a Costa Rica and finished top 3 today.
I see Sérika Guluma and Shoko Kashiki (real surprise in the mountains last year) have already lost bucketloads of time, it looks like it was heavy rain and an absolute demolition derby of crashes out there today.