been applying to a lot of jobs, in my career field and otherwise, and a lot of them are asking if they can contact my previous supervisors. they cannot, because i do not have any way to contact them myself LOL but is this really normal?? who is actually calling those people? is this affecting hiring decisions??


This is a common litmus test. If you parted on good terms you would not object. Its not about the how, but about your reaction. If I see someone flinch I will ask more in that direction and if someone is avoiding and does not seem honest I actually call and ask the full story.
The truth usually resides somewhere between the two stories and that and depending if I think I would want to work with that person, I will hire them. In rare cases with an extended probationary period.
In your situation I would just answer: sure why not? But I don’t have any way to contact them myself, but I can offer the name and company name, so you have something to go on.
Most companies nowadays do not let their employees talky about past employees because of liability.
Send the contact info anyway, HR will tell them they cannot discuss it but usually will answer if the employee is re-hireable or not.
That sounds US specific. I’m from Germany. You are free to ask away, just can’t write bad shit into a letter of recommendation. But you can always offer the call you which is usually a hint not to hire somebody without talking to them.
There are plenty of ways to write bad stuff in recommendation letters that hiring managers will pick up on, without it sounding negative for the employee.
It is US Specific, mostly because that was where I was the last time I worked for anyone else.
…do I need a disclaimer when I write an opinion?
Yes? How are people supposed to know where you live
I mean, you could just take the answer at face value and if it applies to you, heed it or don’t…and if it doesn’t apply just disregard it?
But, you do you, man.