Lol. I used to have a modal till yesterday that asked users to login with Google then removed it as I figured it was just extra friction; didn't realize it was this much of a red flag for websites... I'll readd it, thanks for the feedback.
>>giulio+(OP)
It's a dark pattern regardless. You should be upfront LOUD and clear that login will be required. If people are complaining it's because you're not LOUD and clear enough.
There's a reason that you only see this UX pattern on sleezy lead gen and "Find People Now" stalker'ish sites. And even then they'll give you basic information for free and grab your email and/or money for more "value".