The 2017 MBPro had known design & manufacturing flaws with both the Display Assembly cable and the Butterfly keyboard mechanism. Less know is the design flaw with the I/O Boards which have the USB-C ports. The USB-C ports wear down very quickly with use so that USB-C connections tend to become loose & unstable. Plus unless the battery has been replaced recently, then the battery is likely wearing our or even failing. Most Lithium batteries start needing to be replaced between 3 - 5 years.
If it is the two port non-Touchbar model, then in addition to everything I have already mentioned....the SSD in this non-touchbar model has a very high rate of failure compared to all previous models. The USB-C port wear issue is even worse for this model since the ports are integrated into the Logic Board instead of being housed on a replaceable I/O Board.
macOS 13.x Ventura is the last supported OS for the 2017 model which will stop receiving security updates & support by the end of 2025. Once this occurs it is only a matter of time before apps requiring Internet access for services will start to break as the Internet & web services change (it could be months later, or perhaps years later....no one knows). Any apps for offline use will continue to work just fine unless they need to access documents created by newer apps which may have changed the document layout such as adding new features.
If you are planning on purchasing a used Mac, then be very careful. First, you are purchasing someone else's problem and cast off. Second, this forum is full of posts where these Macs have been locked with a firmware password lock, or are still being managed by the previous owner through an MDM or AppleID.......there is no way for a new owner to remove these security locks & management plus they are not usually evident right away.
If you purchase a used Mac, it is best to purchase one from a reputable vendor such as Apple (refurbished section) or from OWC (a respected vendor supporting Macs for decades). And make sure to perform a clean install of macOS on the used devices even if the previous owner has already done so in order for you to be certain the device is clean since it can alert you to whether a firmware password lock is enabled and possibly whether the system is still being managed by a previous owner. Knowing this immediately after receiving the device should allow you to ask for a full refund if the seller is reputable. Even if you cannot get your money back, then at least you know someone else has control of the device and could erase it at any time (or perhaps even install software remotely if managed by an MDM). You can only start at step #6 when purchasing a used Mac:
What to do before you sell, give away, trade in, or recycle your Mac - Apple Support
