Your 25increase API workflow needs a ‘Chain Door’ parameter of type ‘Chain Door’.
Your Schedule API workflow 25increase on a list will then show another parameter (Chain Door) which you should set to ‘This Chain Door’
Then, instead of make changes to a list of Chain Doors, you should have ‘Make changes to thing’ and change ‘Chain Door’ (the parameter from your API workflow). price = Chain Door’s price * priceinc (so for increase of 25% priceinc should be 1.25)