Apple has confirmed to The Verge that its T2 chip will limit the ability to repair new Macs as it feels that the chip is crucial to enabling modern security features on Mac computers. However, critics are concerned that Apple's move will greatly impact enthusiasts and third-party repair shops thereby preventing them from offering aftermarket services to Mac owners.
https://www.notebookcheck.net/Apple-s-T2-chip-could-severely-limit-the-possibilities-of-third-party-Mac-repair.361166.0.html