I work for a company that was acquired by Google.
Unfortunately, they tell me it is normal for them to rate people in the first year what is now a "M" rating instead of "S".
Question, if I attempt to transfer to a different department at Google when I complete 1 year, is this "M" rating going to be problem?
No.. It is not normal, and they usually do that to play politics. One thing you need to understand about Google... Google is a POLITICAL company.. I have over 33 years of experience in different companies, and I can tell. Google is full of snakes. Some hiring managers might not accept you, but "M" does not disqualify you for internal transfers. Sometimes, you can use this to justify you are looking for a position that matches with your profile. If you have a "M" or "N", believe me, they will put you on the next layoff.
I am also betting you work for fitbit. If yes, move asap.
The TPMO director which now is not only responsible for Fitbit but Home/Devices as well, it is incompetent and lazy but plays politics very well. Check the list of projects cancelled or failed under his resume. He has the perfect googleness and that's why he is there for so many years.