On top of what others have said, I have a few more:
you were hired for a specific team, but you get there and no one on your new team interviewed you (imagine being in their position in 6 months/a year)
you get there and no one is sure what you should work on first (lack of planning)
you don't have a PR raised on day one (or at least have things set up and you're close to getting something small done)
no one takes the time to help you navigate your way through code on your first few tasks
your team uses a process (and I include agile/TDD/pair programming in this) "because it's good practice" without really thinking if it makes sense
lots of meetings are a good indication that people care more about the stuff around developing great things than actually doing it
people on your team don't dogfood (use the product you're working on)
you're only introduced to your team
your team should take you to lunch the first day, or at least take you with them. A great workplace will take you to the pub for lunch/one evening early on, your team will want to get to know you
you feel pressured to work weekends/evenings early on
you feel watched or you have to guard your words/hide what's on your screen (if that happens for any reason at all, get out that day)
there "isn't time" to learn about new tech/libraries/etc that you think could be useful later on
you have someone on your team who rewrites all your code/rips apart your PRs/makes you feel like your a bad developer
everyone on your team should own the code, if you have one person (even someone with a job title like "tech lead") who must review everyone else's code and makes final decisions (or won't stop arguing until they get their way), that's a worry
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
On top of what others have said, I have a few more:
you were hired for a specific team, but you get there and no one on your new team interviewed you (imagine being in their position in 6 months/a year)
you get there and no one is sure what you should work on first (lack of planning)
you don't have a PR raised on day one (or at least have things set up and you're close to getting something small done)
no one takes the time to help you navigate your way through code on your first few tasks
your team uses a process (and I include agile/TDD/pair programming in this) "because it's good practice" without really thinking if it makes sense
lots of meetings are a good indication that people care more about the stuff around developing great things than actually doing it
people on your team don't dogfood (use the product you're working on)
you're only introduced to your team
your team should take you to lunch the first day, or at least take you with them. A great workplace will take you to the pub for lunch/one evening early on, your team will want to get to know you
you feel pressured to work weekends/evenings early on
you feel watched or you have to guard your words/hide what's on your screen (if that happens for any reason at all, get out that day)
there "isn't time" to learn about new tech/libraries/etc that you think could be useful later on
you have someone on your team who rewrites all your code/rips apart your PRs/makes you feel like your a bad developer
everyone on your team should own the code, if you have one person (even someone with a job title like "tech lead") who must review everyone else's code and makes final decisions (or won't stop arguing until they get their way), that's a worry