Are there any pitfalls to avoid in buying PCIe/m.2 adapters?

https://feddit.de/post/2719875

Are there any pitfalls to avoid in buying PCIe/m.2 adapters? - Feddit

I’m planning on giving an older machine a small upgrade with an SSD, but since that machine does not have an m.2 port, I was thinking about buying the cheapest PCIe adapter I could find. Besides the obvious stuff like ports, PCIe gen and lane count, is there anything I should look out for? Specifically regarding Linux?

Startech does a {M.2 SSD to 2.5" SATA drive adapter}(www.startech.com/en-nz/hdd/sat2m2ngff25).
Adapter - M.2 SSD to 2.5in SATA III - Drive Adapters and Drive Converters | StarTech.com New Zealand

M.2 SSD to 2.5in SATA III Adapter with Protective Housing - M.2 Solid State Drive to 2.5in SATA Converter w/ 9.5mm Drive Height - M2 to SATA Adapter | New Zealand

StarTech.com
Unless you are using a SATA NVMe, these either don’t work or seriously bottleneck your performance

He didn’t specify what sort of M.2 SSD he has so I thought that I would throw it out there as an option.

Plus as he said it was for an older computer & was looking for the cheapest adaptor that works, I guessed that he wasn’t too concerned about getting the most performance possible out of the setup.