it does look like its begining to flower.
I would say the underwatering may have played a small part into that. but the plants look like they have also been overfed a bit and autos hate getting to many nutrients from my experience. I have also had autos got into early flower from hot soil "to many nutrients"
Best you can do is grow it out and get what you can from it, or chop it down and start over. all depends how many seeds you got and if your ok with that small loss of time and effort.
Good Luck!
***disclaimer, multiple people are answering all questions as there is a contest called GOTM, when a user is selected as the answer they get a point. Please see the contest page for information regarding the details:
growdiaries.com/giveaways/GotM-August-2022
Please note, when you reply to anything on the questions part of Growdiaries website, no one will be notified of this. Not even if you use a "@" tag in their name. Best to reach out to them in DM using your inbox, it can be found in the bottom right hand corner of the site. It's the small paper airplane button, it will be highlighted green if you have new messages***