Mine is people using are instead of our. I hear this all the time from social media, news reporters, and I see in in writing. Instead of our, they use are as if they forgot the word our exists.
Mine is till instead of ’til to mean until and a in “two times a year” instead of per. I still say “two times a year” myself but when writing it looks so unprofessional and I always notice it in news publications.