problem with membership payment

Good morning,
I have a problem when I want to pay for a subscription.

here is the link to choose a membership: https://izystud.fr/nos-offres/

When I press the button to choose a subscription, they redirect me to the payment page.
However, for any membership, he always asks me to pay the same price.

My first subscription is:
Izystud 6 months and costs €12.50 per month. When I choose it, it redirects me to this url: https://izystud.fr/paiement-dadhesion/?pmpro_level=16
it’s the right level but not the right price, I’m being asked to pay 9.50/month instead of 12.50.

The price of 9.50 corresponds to my second plan which corresponds to level 20.

On the other hand, if we press the button to pay the 9.50/month, I am directed to the correct URL: https://izystud.fr/paiement-dadhesion/?pmpro_level=20
It’s the right price and the right level.

And this problem persists with all the memberships that I create.
Each time it’s the right url with the right level written inside but I’m always asked to pay for the level 20 subscription.

thanks for your help

The page I need help with: [log in to see the link]