Sony is a big player as a console manufacturer. Sony also has a dominating position in the current console generation because of the high commercial success of the playstation 4.

They use their market position to unfairly implement a security chip in their peripherials to prevent other companies from competing with cheaper peripherial products. Some big hardware manufacturers can license their hardware to sell official Playstation 4 compatible products. Other manufacturers are not big enough to buy those licenses for the products.
Technically there is no such reason to prevent hardware from being compatible with the Playstation 4. USB is a common used open standard which connects peripherials for example to the Playstation or home computers or any other current sort of device. Sony adds a security system in form of a hardware chip which prevents unlicensed hardware from staying connected to the PS4 for longer than 8 minutes.
Several manufacturers released a bunch of converter devices which enabled almost every legacy periphery (i.e. Arcade Sticks for Fighting Games and Steering Wheels for Racing Games) to work with the PS4. They found a way to authenticate with Sonys security system. A lot of users bought the converters to reenable their expensive legacy hardware. After an PS4 software update (Update 3.11), these devices stopped working, apparently because Sony banned them. They are now affected by the 8 minute timeout as well, which makes them unusable for competitive gaming because of the timeout.

Sony leverages their market position to unfairly prevent other companies from competing.

We can't accept this and want Sony to refrain from that strategy and stop proceeding against converter and third party Manufacturers.