After seeing the photo, you are over reacting. That looks like good construction. The plywood joints need to be blocked to eliminate movement. There are foam type rolls you buy to put on the plywood before the flooring. This is a place not to go cheap. It will make your floor quiet and act as a moisture barrier. It’s about 1/8 thick. Watch some YouTube videos to build your confidence. It’s pretty easy! Just get your first row straight. Allowing for expansion against the walls are where people make mistakes. I’ve been in the construction trades for over 45 years. There are several here that have the knowledge based on what I’ve read.
