Key malfunction on one key 't'

[algernon (Gergely Nagy)]

See here:

What to do if your keyboard seems to duplicate keystrokes or a key stops working

A number of Model 01 keyboards from the first two production runs developed ‘key chatter’ problems, either over the first few weeks of their lives or later on. This usually manifests as repeated keystrokes. For example, if you type ‘r’, the keyboard might instead send ‘rr’ or ‘rrr’ some or all of the time. Sometimes, it manifests as missing keystrokes. After the second production run of Model 01s, we got Matias to change their keyswitch assembly process to use a dry teflon lubricant instead of …

In short, mail help@keyboard.io, and they’ll walk you through your options. Your keyboard will be fine in the end, one way or the other.