Welcome! Thanks for joining the PayPal Community Forum. I can understand it can be a bit confusing to see an authorisation like this during a Pay in 3/4 payment plan. I've pulled a Help Center article I think may shed some light here: Why is there a pending authorisation shown in my PayPal activity for my Pay in 4 Transaction?
I hope that helps, however you're welcome to reach out to our Customer Support teams by clicking "Contact" at the bottom of any PayPal page for further assistance.
- Jon K
If you find this or any other post was helpful, make our community better by giving kudos or accepting it as a solution.