Quick OpenBSD/thinkpad question

[me]

In browsing through misc@ I am seeing many openbsd users running obsd on 
thinkpads. I had heard quite a bit of rhetoric claiming that Lenovo has 
been building backdoors into their products, yet I could never find 
evidence confirming or disproving these claims. Erring on the side of 
caution, I had decided to simply not use Lenovo.

Years later, I am now revisiting this after seeing that openbsd users & 
devs seem comfortable using Lenovo.

My question is; Does anyone have any insight into these claims, whether 
it be proving or disproving?

Thank you,

-JF