Dad's - why are we adding an apostrophe in the plural of dad?

I see this a lot. The plural of dad is dads. People are putting that apostrophe in dads and then they don't use it in other plural words in their posts. So odd.

Is it an autocorrect thing? Writing this post, my phone has attempted to correct me incorrectly.

Is it an English as a second language thing for those posters?