Do Oregon Mail-in Ballots deny voters their rights to vote?

Four people in our household voted. Three votes counted. One was rejected because they did not like the signature match! WTF!

How can the people at the election office get away with this? If you present to vote in another state, they don't have the option to just reject your vote and tell you about it later. With mail-in, you are not there to represent yourself.

Young people are particularly vulnerable in this regard; they do not have "signatures" like South American bankers--precisely the same difficult swirls every time. This is an antiliberal bias, it seems.

Anyone know what the percentage of rejected ballots are?